Steak and Everything

1/2 lb. round steak or flank steak
2 T soy sauce
1/2 T sugar
1 T butter
2 small green peppers or other colored peppers
2 medium sweet onions
1/2 lb. mushrooms
grated mozzarella or jack cheese

Wipe steak with damp paper towel. Cut into thin slices, 1/2 inch on the diagonal (Partially freeze meat for easier slicing). Combine soy sauce, sugar, 1 T water. Place steak in mixture to marinate for 30 minutes. Chop peppers, onion and mushrooms and saute in butter about 10 minutes. Remove from pan and keep warm. Add oil to pan, add steak and marinade. Stir fry until brown, 3-4 minutes. Add vegetables until liquid is almost gone. Add cheese and put on toasted buns.