1.Combine lamb and half the sauce in a medium bowl. Cover and refrigerate 30 minutes.
2.In batches, stir-fry lamb in a heated oiled wok over high heat, until browned. Remove from wok.
3.Add stir-fry vegetables, water and half the green onion to the wok until vegetables are almost tender. Return lamb to wok with remaining sauce; stir-fry until hot. Season to taste.
4.Serve stir-fry topped with remaining green onion.