Using a sharp knife, cut flank steak across grain into very thin slices.
Blend soy sauce and the 1 tablespoon oil into the cornstarch; pour over beef slices, stirring to coat.
Bias-slice asparagus into 1-inch pieces.
Drop asparagus into a pah of boiling water.
Simmer for 1 to 2 minutes; drain.
In wok or skillet heat the 3 tablespoons oil till sizzling.
Sprinkle sugar over oil." Add beef; cook and stir for 1 minute.
Add asparagus; cook and stir 1 minute longer.
Add sherry and chicken broth; cook 1/2 minute longer.
Arrange meat and asparagus on serving platter.
Serve with hot cooked rice, if desired.