Slice the meat across the grain in 1x1/4 inch strips. Sprinkle the beef with cornstarch and soy sauce. Toss to mix, and set aside.
Bring a pot of water to a boil and add the broccoli; return the water to a boil and cook 2 minutes. Drain immediately. Set aside.
Heat the oil in a wok or large non-stick skillet until very hot. Add the onion and gingerroot and stir-fry about 30 seconds.
Add the steak and stir-fry about 2 minutes to brown the edges of the meat. Add the broccoli, sherry, and 2 tablespoons water. Stir constantly until steaming hot, about 1 minute.
Nutritional Information Per Serving (about 1-1/4 cups):Calories: 295, Fat: 16g, Cholesterol: 54mg, Sodium: 401mg,Carbohydrate: 13g, Dietary Fiber: 4g, Sugars: 6g, Protein: 26gDiabetic Exchanges: 2 Vegetable, 3 Medium-Fat Meat