1.In a medium bowl, combine lamb, allspice, sugar and sauce. Drain lamb; reserve marinade.
2.In a wok, heat half the oil; stir-fry lamb, in batches, until browned. Remove from wok.
3.Heat remaining oil in wok; stir-fry beans, mushrooms and reserved marinade until mixture boils and vegetables are tender. Return lamb to wok; stir-fry until hot, season to taste.
Serve with steamed rice. Lamb mixture can be marinated for a few hours or overnight in the fridge.Note