Yogurt Flank Steak

With a knife, score flank steak on both sides without cutting through. Spray a large skillet with vegetable cooking spray, heat over high heat, and sear the steak quickly on both sides. Remove to a cutting board and cut into very thin slices. In the skillet combine chopped onion, beef broth, chopped parsley, ketchup, prepared mustard, and white wine. Cook uncovered for about 10 minutes, or until the onion is tender. Combine yogurt and flour and stir into the sauce skillet mixture. Add the sliced beef. Heat through but do not boil.