Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain.
Heat oil in a large skillet over medium heat. Saute steak strips for 10 minutes. Stir in green and red bell pepper, mushrooms, tomato and onion. Cook for 10 minutes, or until vegetables are tender. Serve over pasta.
