Rub pepper onto both sides of steaks. Grill, covered, over medium heat or broil 4 in. from the heat for 6-8 minutes on each side or until meat reaches desired doneness (for medium-rare, a thermometer should read 135°; medium, 140°; medium-well, 145°).
Meanwhile, in a large skillet, saute mushrooms in butter for 3-4 minutes or until tender. Add garlic; cook 1 minute longer. Stir in flour until blended. Gradually stir in the broth, wine and salt. Bring to a boil; cook and stir for 2-3 minutes or until thickened. Serve with steaks.