1. In a small bowl, whisk together vinegar, oil, honey and rosemary. Reserve 2 tbsp and add the rest to a 1-gallon zip-top bag. Add pork to bag and refrigerate for 1 hour, turning occasionally.
2. Preheat broiler to high or coat a grill pan with cooking spray and heat to medium-high over stove. Remove pork from fridge, discard marinating liquid and season pork with salt and pepper. Broil pork or cook in grill pan until pork is opaque throughout and feels firm to the touch, or until internal temperature registers 160°F on an instant-read thermometer, about 5 to 6 minutes per side.
3. Meanwhile, cook peaches under broiler or in a grill pan over medium heat until tender and juicy, 3 to 5 minutes. Transfer to a plate, season with pepper and brush with reserved 2 tbsp marinade. To serve, place a pork chop on each of 4 plates and top with 2 peach halves. Garnish with thyme leaves.