Marinate the meat in lemon juice,soy sauce,pepper and salt for 3 hours or more.
Cook onion rings in oil until transparent.Transfer to a serving dish,leaving the oul in the skillet.
Add the meat to the skillet and cook over high heat,stirring often,until tender. Transfer the meat to a serving dish. Add marinade and water to the skillet,simmer for 10 minutes and pour over the meat and onion rings