Grated Parmesan cheese Partially freeze beef, thinly slice across grain into bite-size strips.Combine water, vinegar, onion, pepper and red pepper.Add meat, Mix well.Marinate 15 minutes @ room temperature.Cook pasta according to package directions.Drain;toss with butter.Keep warm. Drain meat,reserving marinade.Stir cornstarch into reserved marinade; set aside.Stir-fry garlic in 2 tbsp. oil for 30 seconds.Add meat;stir fry 3 minutes.Remove.Add remaining oil.Add frozen vegetables;stir-fry 4 minutes.Add mushrooms;stir-fry 1 minute.Stir marinade mixture;add to skillet.Return meat.Cook and stir until bubbly.Cook 2 minutes.Arrange pasta and meat on platter.Sprinkle with cheese.Serves 4.