Beef Stroganoff without peas clove

1 cup onions thin-sliced 3 tablespoons vegetable oil divided 3 cups mushrooms sliced 1 1/2 pounds beef, flank steak cut across grain into thin slices 1/3 cup[...]

3 tablespoons corn oil 1 pound beef top round or flank steak cut in small strips 1/2 pound mushrooms sliced 1 cup onion sliced 2 cups beef broth 1 tablespoon[...]