Combine vinegar, brown sugar, orange juice, garlic, olive oil, salt and pepper in a large ziplock bag. Seal and shake to combine. Cut pork chops into 1 1/2” cubes and add to bag. Seal and refrigerate for 1 hour or up to one day. Remove pork from marinade. Place the marinade, minus the garlic, in a small saucepan. Heat the marinade to boiling and boil until slightly thickened and reduced by half, about 5-7 minutes. Reserve. Skewer the pork, apples, and onions. Sprinkle with salt and pepper. Heat grill pan to medium high. Drizzle pan with a little oil. Place skewers on the pan and grill for 4 minutes. Turn quarter of the way around and grill another 4 minutes. Repeat for 2 more sides for a total of 16 minutes. Serve over rice and drizzle with reduced marinade.