Blend soup, milk, sour cream, salt and pepper in small bowl; set aside.
Cook and stir onions and garlic in hot margarine in nonstick skillet over medium heat until lightly brown. Add sugar; cook until golden, stirring constantly. Stir in vinegar; cook 1 minute. Remove from skillet; set aside.
Add mushrooms to skillet; cook and stir until lightly brown. Remove from skillet; set aside.
Add steak; cook and stir over high heat until browned on both sides. Remove from skillet; drain skillet.
Add soup mixture to skillet; cook over low heat until heated through. Return onions, mushrooms and steak to skillet. Heat 2 minutes. (Do not boil.) Serve over hot cooked noodles; garnish with parsley.
This recipe yields 6 servings.
Exchanges Per Serving: 3 Starch, 1 Meat, 2 Vegetable.
Nutrition Facts: Calories 330; Calories from Fat 14%; Total Fat 5g; Saturated Fat 2g; Protein 14g; Carbohydrates 56g; Cholesterol 35mg; Sodium 541mg; Dietary Fiber 1g.