Mongolian Beef

++ ++ Preparation: Cut tops of green onions into 2" long pieces. Combine sauce ingredients in small bowl & stir thoroughly. Cut steak across the grain into thin slices, about 1/2" deep by 2" long. In bowl big enough to hold meat, combine egg whites, salt & water chestnut flour. Beat with chopstick until frothy. Add steak, & use fingers to coat each slice. Deep-frying: In wok, heat oil to moderately hot. When ready, piece of coated meat will rise to surface immediately. Fry meat in small batches; drop in 1 slice at a time to avoid sticking. Cook until lightly brown, about 1 minute. Drain on Chinese strainer or paper bag. Stir-frying: Remove all but 2 T of oil from wok. With wok at medium heat, quickly stir-fry green onions & ginger for about 20 seconds. Add sauce; bring to boil on high heat while stirring. Add beef all at once, & toss with sauce until beef is hot & coated. Push beef out of sauce, dribble in cornstarch paste to lightly thicken. Recombine. Serve immediately.