Combine lamb and marinade ingredients, mix very well. Cover and refrigerate to marinate and tenderise the lamb.
Marinate for 2 hours for tender cuts, or 24 hours for economical cuts.
Mix cornflour with the soy sauces, then mix in the remaining sauce ingredients.
Heat oil over high heat in a wok or heavy based skillet. Add onions, and stir fry for 30 seconds until starting to colour. Add garlic and toss through quickly.
Add lamb and cook for 3 minutes until most of it changes from red to brown.
Add green onions, stir for 30 seconds, then add Sauce. Stir and let simmer for 1 - 2 minutes until thickened.
Serve with rice.
