In a small bowl, stir together mustard, apple juice, molasses, Worcestershire sauce, and pepper. Set aside.
Trim fat from the steaks. Coat grill with nonstick cooking spray. Preheat grill to medium direct heat. Grill steaks, uncovered, to desired doneness, turn once halfway through grilling and generously brush with sauce during the last 5 minutes of grilling. Allow 11 - 15 minutes for medium rare or 14 - 18 minutes for medium. Serves 4