1 boneless beef sirloin or top round steak, ¾” thick, thinly sliced (about 1-1/2 lbs.)
1 Tbls. oil + 1 Tbls. butter
1 large onion, thinly sliced (about 1c.)
8 oz. sliced mushrooms
1/4 c. good balsamic vinegar (18 yr or older)
1 c. Prego Traditional Italian Sauce
1/2 c. crumbled gorgonzola or feta cheese
In a large skillet, heat oil and butter, over medium-high heat. Add the beef in 2 batches and cook until it’s well browned, stirring often. Remove beef from the skillet. Pour off any fat.
Reduce heat to medium. Add mushrooms and onions and cook for 5 minutes or until tender. Stir in the vinegar and cook for 2 minutes.
Stir in the sauce and heat to a boil. Return beef to the skillet. Top with cheese. Cook and stir until the cheese is melted