1. Heat oven to 400 degree F.
2. Heat oil in large ovenproof skillet over medium-high heat 1 minute. Sprinkle pork with 1/2 teaspoon salt and 1/4 teaspoon pepper. Brown pork 3 minutes per side; add vinegar and soy sauce. Bake 8 to 12 minutes, until instant-read meat thermometer inserted in center of one chop reaches 155 degrees F. With slotted spoon, transfer pork to cutting board. Transfer sauce to bowl; keep warm.
3. Add butter and spinach to skillet. Cook over medium-high heat 1 minute, until spinach wilts. Sprinkle with a pinch each salt and pepper. Slice pork and arrange on 4 serving plates. Serve with spinach and balsamic sauce. Makes 4 servings.