Add olive oil to your pot and heat over high heat. Add the lamb roll and sear until brown all over, approx five minutes. Turn off the heat and remove the lamb and set it aside.
Half and thickly chop your onions, and chop up the rest of the mushrooms the same way you did before. Then thinly slice your garlic cloves.
Turn the stove back onto medium-high heat, add the onions and garlic and stir for a minute. Then add the mushrooms and cook while stirring until tender.
Add the wine and chicken stock, followed by the barley, finely chopped mint leaves and bay leaves. Stir and then allow to cook until it just boils. Refer to notes if you do not want to use wine.
Add the crushed tomatoes and stir through, then the sprigs of fresh rosemary in the centre, and place the rolled lamb breast on top.
Put the lid on your pot and place it in a preheated fan-forced oven of 170°C for 2½ hours.