Pat the lamb down with a paper towel and cut 2cm long slits into the skin with a sharp knife. Slice garlic into slivers and insert one piece into each cut that you made into the skin.
Drizzle the lamb with olive oil and season with sea salt and cracked pepper around the entire lamb.
Preheat your air fryer to 180°C (355°F) for 2 minutes. Then place your leg of lamb inside the basket. Set a timer for 20 minutes at the same temperature of 180°C (355°F).
In a small mixing bowl, add boiling water, brown sugar and salt and stir until dissolved. Finely chop mint leaves and add to the mixing bowl with malt vinegar, stir and set aside.
After the first 20 minutes, generously baste the lamb with the mint glaze over the entire lamb. Then set the timer on your air fryer for a further 20 minutes.
Continue to baste the lamb every 20 minutes until you have reached the desired doneness, keeping the temperature of your air fryer at 180°C (355°F). (See Note 2). Use any remaining glaze to baste over the lamb during the last stage of roasting.
Use an instant-read thermometer to check your lamb for the desired doneness.
Once the lamb has reached your desired doneness wrap, it up in aluminium foil and rest for 10-15 minutes. Carve and serve.