In a small bowl, mix the sherry, oyster sauce, sugar, and cornstarch.
Heat the oil in a skillet, and cook the flank steak about 3 minutes. Stir in sherry sauce mixture. Add the green onions, and continue cooking 10 minutes, or until the flank steak is evenly brown and the green onions are tender.
Beef with Green Onion · Dinner Match Lab | Dinner Match Lab