Heat 1/2 teaspoon oil in a large skillet over high heat. Add half of veal, and cook 4 minutes; turn and cook 1 minute. Transfer cooked veal to a plate, and keep warm. Repeat with remaining 1/2 teaspoon oil and veal.
Coat pan with cooking spray; add mushrooms and onion; sauté 5 minutes or until mushrooms are tender. Stir in butter and next 6 ingredients. Bring to a boil; cook 5 minutes or until thickened, stirring occasionally. Spoon sauce over veal. Sprinkle with parsley.