Partially freeze steak; slice across the grain into ⅛’ strips.
Combine water, sherry and soy sauce; pour over beef and marinate 1 hour.
Stir-fry vegetables in 1 tablespoon oil in large skillet over medium-high heat. Remove from skillet; set aside.
Remove beef and reserve marinade. Brown beef in remaining 1 tablespoon oil. Combine cornstarch with reserved marinade. Add vegetables and marinade to beef; cook, stirring, until sauce is thickened.
