Trim fat from beef; cut beef into strips, 2 x 1 x ΒΌ inch.
Heat oil in large skillet. Add beef; cook, turning frequently, until brown, about 5 minutes.
Stir in water, onion, garlic salt and ginger. Heat to boiling; reduce heat. Cover and simmer 12 to 15 minutes for round steak, 5 to 8 minutes for sirloin.
Add green pepper strips during last 5 minutes of simmering.
While beef simmers, cook instant rice as directed on package for 4 servings.
Blend cornstartch, sugar and soy sauce; stir into beef mixture.
Cook, stirring constantly, until mixture thickens and boils. Boil and stir 1 minute.
Cut each tomato into eighths and place on beef mixture. Cover, cook over low heat just until tomatoes are heated through, about 3 minutes.