In a small bowl combine mustard, Italian dressing, and pepper; set aside.
Trim excess fat from chops. Spray a 10-inch skillet with nonstick cooking spray. Preheat the skillet over medium-high heat. Add the pork chops and brown on both sides. Remove chops from skillet.
Add onion to skillet. Cook and stir over medium heat for 3 minutes. Push onion aside; return chops to skillet. Spread mustard mixture over chops. Cover and cook over medium-low heat for 15 minutes or until juices run clear. Serve onion over pork chops. Makes 4 servings.