Place the lamb and onions in a large, heavy-based casserole with the water, oil, half the butter, the cinnamon stick, saffron and ginger. Season, then cover the dish and cook over a medium heat for 20 minutes.
Meanwhile, peel and core the quince and cut into eighths. Put the remaining butter, the ground cinnamon, sugar and honey in a saucepan and moisten with 2 ladlefuls of the cooking juices from the casserole.
Tip in the quince and cook until they are caramelized.
Transfer the meat to a round serving plate and serve with the sauce and the quince.