Step 1: Cut the beef into slices. Put them into a bowl. Mix soy sauce, sesame oil, rice wine or sherry, and cornstarch in seperate bowl and stir until cornstarch dissolves.Add mixture to the beef. Let the meat marinate for 10-20 minutes. Heat a wok until it is very hot, then add the oil oil should be smoking.Add the beef slices and stir-fry for 5 minutes or until lightly browned. Remove the meat from the wok and drain well in a colander set over a bowl. Discard the drained oil. Wipe the wok clean and reheat it over a high heat. Add the oyster sauce snd beef and bring it to a simmer. Turn beef so all pieces are coated. 5 mins before serving add a handful of scallions to the meat and stir. Take off heat and serve, garnish with the scallions, and serve with rice. Leftover meat makes a great steak sandwich. Dont use too many scallions, you dont need that many.