1 tablespoon vegetable oil
1 lb. boneless beef sirloin steak, cut into 1×1/4-inch strips
1 (1-lb.) pkg. frozen broccoli florets, carrots and cauliflower (Or any combination of vegetables you want)
1/2 cup purchased stir-fry sauce
1 teaspoon cornstarch
In a large skillet, heat oil until hot. Cook the beef and stir frequently for 5 to 6 minutes or until no longer pink. Drain. Add vegetables.
In small bowl, mix together the stir-fry sauce and cornstarch. Pour over vegetable mixture; stir to combine. Reduce heat; cover and simmer 6 to 8 minutes or until vegetables are crisp-tender, stirring occasionally.
Serve over rice or buttered noodles