Beef Stroganoff Casserole

1/2 cup chopped onion 2 tablespoons butter 1 lb lean steak, cut in thin strips or 1 lb hamburger 2 tablespoons flour 1 teaspoon salt 1/2 teaspoon black pepper[...]

8 ounces rotini noodles 1 lb ground beef 1 medium onion , chopped 1 clove garlic , minced 1 teaspoon oregano 1 teaspoon salt 1 teaspoon pepper 2 (15 ounce)[...]

1 lb lean ground beef 1/4 teaspoon salt 1/8 teaspoon black pepper 1 teaspoon vegetable oil 8 ounces mushrooms , sliced 1 large onion , chopped 3 cloves garlic[...]