Rub both sides of pork chops with thyme, pepper, and salt. Cook pork in a large nonstick skillet coated with vegetable cooking spray over medium-high heat 2 minutes on each side. Add oil; cover, reduce heat, and cook 3 minutes. Remove pork from skillet.
Sauté onion, bell pepper, and garlic in skillet until crisp-tender. Return pork to skillet, and cook 2 minutes. Cover, reduce heat, and cook 9 minutes or until pork is done. Drizzle with vinegar. Garnish, if desired.