Thinly slice beef on the diagonal (for easy
slicing,place meat in the freezer until slightly
frozen);place in a snug-fitting bowl.Combine soy
sauce,sherry,garlic,and black pepper;pour over
meat,tossing to coat completely.Cover and refrigerate
8 to 10 hours.
In a large skillet or wok,heat oil. Add green pepper
and onion saute for 2 minutes.Dissolve bouillon cube
in boiling water. Add beef and marinate.Bring to
boiling point.Reduce heat and simmer,covered for 8
minutes.Blend cornstarch with cold water. Stir into
mixture in skillet.Cook and stir until thickened.Cut
tomatoes into wedges;add to skillet;stir gently.Cover
and simmer, just until tomatoes are hot,about 3
minutes.Serve hot over rice with scallions,if
desired.Serves 6 to 8.