Stack beef round tip steaks on cutting board; cut crosswise into 1-inch strips. Cut strips into 21/2-inch pieces. Combine soy sauce, sherry, water and cornstarch; mix well. Place beef and marinade in plastic bag, turning to coat. Close bag securely and marinate at room temperature 15 minutes. Meanwhile, heat large non-stick skillet or wok over medium-high heat 5 minutes. Drain beef; reserve marinade. Add oil and stir-fry beef and garlic (1/2 at a time) 1-2 minutes or until beef is barely pink in center. Reduce heat to medium. Add onion; stir-fry 1 minute. Add vegetable medley; stir-fry 2-4 minutes or until vegetables are hot and tender-crisp. Return beef and accumulated juices and the reserved marinade to skillet. Heat 1 minute or until beef is heated through and sauce is slightly thickened. Mak es 4 servings. PREP TIME: 10 minutes. Marinate: 15 minutes. Cook time: 6-10 minutes From the files of Al Rice, North Pole Alaska. Feb 1994