Step 1

Heat the oil in a flameproof casserole dish over a high heat, add the lamb trimmings (if using) and cook until crisp. Remove using a slotted spoon and set aside. Keep the dish on the heat but reduce to the lowest setting, add the shallots and cook for 15 mins.

Step 2

Tip in the lentils and stir well to coat. Pour over the beer and let it bubble until almost all of it has evaporated. Return the crispy lamb trimmings to the dish (if using), add the stock and stir through the thyme. Simmer gently for 25 mins or until the lentils are just cooked. Pop on a lid and set aside, then reheat when the lamb is ready.