Sprinkle pork chops with pepper. In a large nonstick skillet coated with cooking spray, brown chops in oil. Remove and keep warm. In the same skillet, saute onion and shallots until tender. Add broth and wine, stirring to loosen browned bits from skillet. Bring to a boil. Reduce heat; simmer, uncovered, for 3 minutes.
Return chops to skillet. Cover and cook 8-10 minutes longer or until meat is tender. Place chops on a serving platter and keep warm. Stir mustard into skillet. Return to a boil. Reduce heat; simmer, uncovered, for 12-15 minutes or until sauce is thickened. Spoon sauce over chops; sprinkle with celery leaves.