Put the lamb shanks in a large saucepan and cover them with water. Bring to the boil and remove any scum from the surface of the water. Reduce the heat and simmer for 1 hour. Remove the shanks and drain.
Heat the oil and butter in a large copper pot or heavy-based saucepan over a medium heat, add the lamb shanks and cook for 3–4 minutes, turning occasionally, until browned all over. Remove the lamb shanks and set aside.
Chop the celery and carrots into bite-sized pieces and add them to the pan with the shallots and garlic and cook for 2–3 minutes, then add the cumin seeds, cinnamon sticks, chickpeas, kidney or fava beans and tomatoes and return the shanks to the pot or saucepan. Pour in the stock and season well with salt and pepper. Bring to the boil, then reduce the heat, cover and cook gently for 1½ hours.
Mix together the chopped mint and preserved lemon in a bowl and sprinkle the mixture over the k’dra. Serve with chunks of bread, if liked.