1 pound rounds beef sirloin tip steaks
1/2 cup vegetable oil
1 (16 ounce) package mushrooms, sliced
1 tablespoon olive oil
1/2 cup chopped onion
1 small tomato, seeded
1 (5 ounce) can tomato paste
1 1/2 cups shredded Swiss cheese
2 teaspoons dried basil
salt and pepper to taste
In a large resealable plastic bag, mix vegetable oil, mushrooms, olive oil, onion, tomato, tomato paste, Swiss cheese and basil. Secure bag using toothpicks.
Cover bag tightly with plastic wrap and refrigerate 1 1 hour. Reduce heat to low and continue cooking, stirring occasionally, until beef is no longer pink and cheese is melted.