Sprinkle chops with salt and pepper. Heat oil in a large nonstick skillet over medium high heat. Add chops, and cook 2 to 3 minutes on each side. Remove chops from pan and keep warm. Add onion to pan. Cover and cook over medium high heat 6 minutes or until tender, stirring occasionally. Add vinegar; cook 30 seconds, stirring constantly. Sprinkle with brown sugar; cook 1 minute, stirring constantly. Spoon onion mixture over pork chops