Combine first 4 ingredients and coat steak on both sides. Place in shallow dish. Cover and refrigerate 8 hours.
Place on rack coated with cooking spray and place in broiler pan. Broil 4" from heat (with electric oven door partially opened) 4-5 min on each side or til desired degree of doneness. Let stand 5 min. Thinly slice across grain and keep warm.
Coat skillet with cooking spray and cook mushrooms over medium heat, stirring constantly til tender. Gradually add flour, broth and 1/2 cup wine and cook stirring constantly til thickened. Stir in salt and pepper. Serve over meat.
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Mustard Marinated Sirloin recipe