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Juicy Weber Q Roast Lamb with Garlic and Rosemary

by Shannon

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If you’re a novice to cooking on your Weber Q, then you’re in for a treat. This recipe will guide you step-by-step on how to make the most delectable and juicy Weber Q roast lamb you’ve ever tasted. Whether you’re planning a special occasion or just looking to impress your guests, this dish is sure to steal the show.

weber q roast lamb

Hooray, the weekend has arrived, and you have guests over! But what’s on the menu? If you own a Weber Q, you’re in luck. Follow my detailed guide and discover how to make mouth-watering Weber Q roast lamb that will impress your guests every time.

Don’t worry if you’re new to cooking lamb on your Weber Q, my foolproof method will make you a pro in no time. With juicy results every time, this recipe is sure to be a hit with your friends and family. Keep reading to learn how to master the art of Weber Q roast lamb.

How to Prepare Your Weber Q for Roasting?

A Weber Q is a versatile cooking appliance that combines the functionalities of a BBQ and an oven. However, these two cooking styles are vastly different, and it’s crucial to keep this in mind while using it.

To cook the perfect Weber Q roast lamb without burning the bottom, it’s essential to transform your Weber Q into a convection oven. This conversion will ensure even cooking and allow the meat to cook to perfection.

Weber Q Roast Lamb
Weber Q Roast Lamb

To convert your Weber Q into a convection oven, you’ll need an aluminium convection tray and a trivet to elevate the meat above it, allowing heat to circulate. The tray features holes that allow fat to escape and drip down through the bottom of the Weber Q.

Before placing any food on the grill, ensure your Weber Q is clean. Excessive fat build-up can pose a fire hazard. Clean your grill, replace the drip tray, and ensure that the bottom hole is clear.

The grill features four grooves, two on each side. Place the convection tray into these grooves to prevent it from moving around. Then, position the trivet in the centre of the tray.

Now it’s time to preheat your Weber Q BBQ before cooking.

How to preheat the Weber Q?

To preheat a Weber Q, you should follow these steps:

  1. Make sure the grill is clean, and the drip tray is empty.
  2. Open the lid and turn on the gas supply.
  3. Turn both gas control knobs to the Start/High position.
  4. Press the red ignition button until you hear the gas flowing.
  5. Close the lid and let the grill preheat for at least 10 to 15 minutes.
  6. Check the temperature gauge or use a digital meat thermometer to confirm the grill has reached the desired temperature before placing any food on the grill.

It’s important to note that the preheating time may vary depending on the model and size of your Weber Q, as well as the desired cooking temperature. Always refer to your Weber Q owner’s manual for specific preheating instructions.

It’s time to make some yummy lamb crackle!

Once your Weber Q has been preheated, we need to turn down the small control knob to the low position, after all, we don’t want to charcoal our meat.

Next, place your lamb onto the centre of the trivet, and listen to it sizzle hmmm.

If you have a meat probe, insert it into the centre of the meat.

If your lamb has a bone, make sure not to let the probe touch the bone otherwise the internal temperature of the meat will give you a false positive. In other words, it won’t be accurate.

The reason we cook the Weber Q roast lamb at such a high temperature for a short time is to begin to get the skin to crackle quickly.

If the temp is too low when putting in our meat, it will not have enough heat to crackle the skin. Instead, it will be soft and rubbery during the cooking process.

Continue to cook with the small knob on the low setting and the large knob in the high position for 25 to 30 minutes. Please try not to be tempted to lift the lid during this time.

Trust your Weber Q to do its job.

What is the roast setting on a Weber Q?

After you have blasted your lamb with heat, we need to turn it down.

You will want to turn off the small control knob completely. And turn down the large control knob to the medium setting.

Provided your Weber Q is not out in the open air on a windy day, you should not need to change this setting again.

But just in case there is a lot of fluctuation in the temperature, you can adjust the roast control knob between the HI/MEDIUM setting to keep the temperature within the ballpark of where it needs to be to roast.

What is the roasting temperature on a Weber Q?

If you have an iGrill 2 meat thermometer, then this will be easy for you to monitor.

The Weber Q was never designed to be like the Weber kettle where you can roast at temperatures as low as 170°C to 180°C

This bbq needs heat to do its job correctly.

To successfully achieve a juicy Weber Q roast lamb, you need to maintain the temperature between 190°C to 230°C at all times. Or 375°F to 450°F.

You should also make sure to keep the Weber out of the wind and the elements, as this will cause it to struggle to maintain its correct temperature.

And you will often find yourself battling to keep the temp within this zone if left in the elements.

Can I roast vegetables in a Weber Q?

Absolutely! And I encourage it. Especially if you’re fortunate enough to have the Weber Q medium or family series BBQ.

If you’re cooking a succulent roast pork, lamb, or chicken on your Weber Q, why not add some potatoes and pumpkin on the side? I always do, and it’s a game-changer!

The savory and smoky flavors from the lamb will seep into the veggies, giving them a delicious and unique taste.

But timing is key here. I suggest adding your veggies to the trivet when the meat’s internal temperature reaches around 30°C or 86°F.

Don’t take too long adding the vegetables as it will let the heat escape, and you don’t want that. So, quickly put them in and close the lid.

And one more thing, don’t forget to adjust the roast control setting if needed, depending on the quantity of vegetables you’ve added.

Trust me, your taste buds will thank you!

How long does it take to cook a Weber Q roast lamb?

To know the time it takes to cook a Weber Q roast lamb is dependent on its weight and thickness.

I go by either method. This takes me back to when I talked earlier about the importance of having a meat probe in your arsenal.

Because honestly if you have one of these, it doesn’t matter. A roast of any kind will cook when it cooks.

But to give you an example: If I have a roast that weighs approximately 2 1/2kg then I know I am going to be looking at about 2 1/2 hours to cook.

It is generally 1hr of cooking time to every 1kg of weight. This method worked for me in my Weber kettle days because I was cooking my roast lamb at around 180°C.

But trying to do this method on a Weber Q is impossible, because of the higher temperatures it will cook your meat. The Weber Q was never designed to cook meat at such low temperatures.

The other method is to measure the thickness of the meat. We do this because meat absorbs heat from the outside to its core. Theoretically the thicker the meat, the longer it will take to cook.

Place a ruler at the large and thickest part of the lamb. Make a note of the measurement and do some quick maths.

For every millimetre, you add one minute of cooking time. For example, if a lamb roast was 110 millimetres thick, it would take about 110 minutes of cooking time.

I tend to not worry about doing this and rely on my iGrill meat thermometer.

I always allow extra time to preheat, blast the skin for 25-30 minutes and finally, the roasting faze. And I still manage to have my roast rested and served before 6 pm, after starting the whole process at about 2:30 pm.

What should the internal temperature of roast lamb be?

Always be mindful of the internal temperature of your Weber Q roast lamb, it is white meat and if consumed while undercooked can make you sick.

Weber Q roast pork

A Weber Q roast lamb is safe to take out of your Weber Q when the internal temperature reaches a minimum of 60°C or 140°F which is considered rare.

  • Rare 60°C
  • Medium rare 60–65°C
  • Medium 65–70°C 
  • Medium well done 70°C 
  • Well done 75°C

Source: Australian Lamb

Allow 15 to 20 minutes to rest as the internal temperature will begin to rise another 3°C during the resting process.

Another way to be sure the meat is cooked perfectly is to make an incision into the side and check if the juice is running clear.

The best part is carving your Weber Q roast lamb!

Like the title above says, this is the best part.

If you have followed my steps correctly, you should have a delicious, juicy lamb roast when you begin carving into it. Your tastebuds will be on overload.

This is the love the Weber Q provides, and I don’t know if I can ever go back to my Weber kettle.

If you had a go at cooking a Weber Q roast lamb, then please let me know how you went in the comments.

If it didn’t work out for you, then I am more than happy to help you figure out where it went wrong.

You can also check out my UlTIMATE WEBER Q GUIDE HERE! Where you can learn everything there is to know about cooking on your Weber Q BBQ.

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Roast Lamb With Rosemary And Garlic

Weber Q Roast Lamb with Garlic and Rosemary

If you are the lucky owner of a Weber Q BBQ your friends and family are in for a treat. Your leg of lamb will be succulant and juicy everytime.
5 from 3 votes
Prep Time 15 minutes
Cook Time 2 hours
Course Main Course
Cuisine Australian, New Zealand
Servings 6 people
Calories 266 kcal


  • 2.5 kg Bone In Leg of Lamb
  • Rosemary Fresh
  • Garlic Fresh
  • Salt
  • Pepper
  • Olive Oil


  • When you are ready to start you will need to get your Weber Q ready for convection oven cooking. Place a new convection tray onto the grill, noticing that Weber Q trays will line up with the holes on the grill, this will prevent movement. Then place a trivet on top of the convection tray.
    Weber Q Roast Lamb
  • Turn on the gas bottle that is connected to your Weber Q and turn both control knobs to the START/HI position. Then push the ignition switch to fire up the BBQ. If you have a Weber Q Baby then turn the control knob to START/HI. If you have 2 meat probes handy, then this is the time to rest the first probe onto the convection tray. This will give you the temperature of the Weber Q BBQ. Run at this setting for 10-15 minutes to get the Weber Q nice and hot, with the lid closed.
    Weber Q Roast Lamb
  • While your Weber Q is heating up, now is the time to prep your leg of lamb. Begin by pealing and cutting fresh garlic cloves into small 1cm pieces. You will need about 12-14 small blocks of garlic.
    Weber Q Roast Lamb
  • Cut 12-14 small pieces of fresh rosemary.
  • Make 12-14, 2cm cuts across the lamb and place 1 piece of sliced garlic and rosemary into each insicion. Making sure to bury the garlic but leave a small amount of rosemary sticking out, so as to remove it later upon serving.
    Weber Q Roast Lamb
  • Baste olive oil over the leg of lamb making sure the entire leg is covered.
  • Sprinkle salt and pepper as desired.

Roasting the Leg of Lamb

  • Place the lamb onto the centre of the Trivet, and if the Weber is hot enough you will hear it sizzle. Now is the time to insert your other meat probe into the centre of the lamb. If your roast has a bone, make sure the probe does not make contact with it, as this will give you a false internal temperature reading. Make sure you remember to close the lid to stop heat from escaping.
    Weber Q Roast Lamb
  • If you have the Family Q series turn down the small control knob to the LOW position and leave the large control knob in the HI position. If you have a Weber Q Baby then don't change any positions on the control knob and continue with this method. Leave your leg of lamb for at least 25 to 30 min at this setting and please avoid the temptation of lifting the lid to check if the lamb crackle process has begun.
    Weber Q Roast Lamb
  • After 30 minutes the lamb will already show signs of crackle. Next, you need to turn the smaller control knob to the OFF position, and the large control knob to the ROAST (middle) position.
    For the Baby Q, simply turn the single gas control knob to the medium (middle) roast position.
    Weber Q Roast Lamb
  • The temperature will be high at first but turning the control knob to the medium position will soon bring the temperature down. And don't worry you won't burn the roast. Keep the roast at between 190°C to 230°C or 375°F to 450°F at all times. You can maintain this easily by keeping an eye on your temperature and adjusting the control between HI and Medium as required.
  • Once the internal temperature of the lamb has reached 45°C or 113°F, it is time to add any vegetables that are required for roasting. Place your vegetables around the roast lamb, so they can absorb the smokey aroma and flavors of the roast lamb.
    Weber Q Roast Lamb
  • Monitor the temperature of the Weber Q and meat throughout the cooking process with your meat probe. Once the internal temperature of the lamb has reached 155°F or 68°C lift the lid and remove the meat probe, making sure to wear gloves so as not to burn yourself. Place the lamb onto a serving plate and set aside to rest for 15 to 20 minutes. This will bring the internal temperature to around 160°F or 71°C. After resting carve your lamb and serve with roast vegetables and ENJOY!


If you love a bit of crackle on the lamb, take a sharp knife and make light slashing motions across the skin in a criss-cross.
Try not to slice into the meat. Only put thin slices into the top slayer of skin.


Serving: 100gCalories: 266kcal (13%)Protein: 23.93g (48%)Fat: 18.15g (28%)Saturated Fat: 7.633g (48%)Polyunsaturated Fat: 1.394gMonounsaturated Fat: 7.533gCholesterol: 92mg (31%)Sodium: 228mg (10%)Potassium: 281mg (8%)Calcium: 16mg (2%)Iron: 1.97mg (11%)
Keyword Weber Q Roast Lamb
Tried this recipe?Let us know please drop a comment below!

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Keran December 25, 2020 - 12:31 pm

5 stars
Can’t I just say, I have been quite overwhelmed by my Weber and a little intimidated by it. But when faced with hosting family Xmas after lockdown laws were enforced, I bit the bullet and gave it a whirl. Thanks to your guidance, I served up a delicious leg of lamb – I was so surprised! So thank you, for helping this rookie (that doesn’t have a thermometer on her Weber, or an igrill-yet) and for giving me the confidence to attempt and nail Xmas dinner. I appreciate it so so much!! Merry Christmas!

Shannon December 25, 2020 - 8:04 pm

That’s awesome, I’m so happy that I’ve been able to help you have a bang-up dinner for your family. Now you will be able to do it perfectly every time…Well done!
Merry Christmas and a safe and happy new year to you and your family.

Brittany Skelsey February 5, 2021 - 10:21 am

5 stars
We had this for dinner tonight. Absolutely beautiful but I could not for the life of me get my weber family q under 240°c!!! I’m not overly worried as the meat just cooked quicker and it was still juicy but any tips would be greatly appreciated

Shannon February 5, 2021 - 9:31 pm

Hey! Thanks for reaching out and I’ll be more than happy to help.
There could be a few factors at play here as to why your temp wouldn’t go under 240C on your Weber Q.
The weather can play a role, depending on the temperature of the day and what part of the world you’re in. If it’s a hot day it can keep temps high for example.
To maintain a temp range between 190C to 230C turn the large gas control knob to the medium roast setting. If the temperature still doesn’t go under 230C turn the gas control knob down to medium-low or low
just enough for the temp to reach around 200C then turn it back up to medium. As long as your roast is between those temps you will have a beautifully cooked roast lamb.
And lastly, if your Weber Q is positioned in the sun, find some shade to cook under. Keeping the Weber Q out of the direct sun will also help to lower the temperature.
I hope that helps you with your next roast.

Maxine July 26, 2021 - 8:28 pm

Going to try this next Sunday Roast 😁 My Webber Q only has 1 knob, It’s a Baby Q with the thermostat in the lid – do I leave it on Hi for the whole cooking process or did I miss something? Thanks in advance 😁

Shannon July 26, 2021 - 8:50 pm

Apologies for the confusion Maxine. After your Baby Q has preheated and your lamb is on the trivet, leave the gas control knob on HI for 25-30 minutes, then turn it down to the roast (middle) position for the remainder of the cook. Good Luck!

Shelly August 24, 2021 - 5:31 pm

I’ve got a Weber Q200 (same as Q2000, just an older model). After heating on high for 10 mins, should i be doing the lamb roast (on the trivet & tray) set at two notches less than medium?

Shannon August 25, 2021 - 8:46 am

Hi Shelly, Your lamb should always be set up for indirect cooking by using a convection tray and trivet. Just place them onto the grill before preheating your Weber Q. Try to maintain a temperature between 190C and 230C at all times during the cook. The medium/roasting position is usually the go-to mark. But if your Weber tends to get too hot, just drop it 1-2 notches below medium to keep it between this temperature range.

Shelly August 24, 2021 - 5:32 pm

Also, would this work with a bone in lamb shoulder?

Shannon August 25, 2021 - 8:48 am

I don’t recommend roasting a lamb shoulder the same way as a leg of lamb. Lamb shoulder is better cooked low and slow as it’s not as tender.

Doc January 15, 2022 - 3:19 pm

5 stars
So I don’t have to turn the roast half way thru cooking?

Shannon January 16, 2022 - 7:52 am

No, just place the lamb onto the trivet and leave it throughout the entire cook. Just try not to peak too often, or you’ll lose the heat.

Jamain March 14, 2022 - 7:19 pm

5 stars
I’d recommend this to anyone, had an amazing roast for a family dinner. Also the first roast I’ve ever cooked.

Shannon March 15, 2022 - 8:18 am

I’m glad you enjoyed it, well done.


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