Combine oil, vinegar, paprika, garlic and 1/4 teaspoon salt in a blender; process until creamy, scraping down the sides as needed. Place sweet potato, potato and onion in a medium bowl. Add the remaining 1/4 teaspoon salt and 3 tablespoons of the sauce; toss well to coat. Rub both sides of pork chops with the remaining sauce.
To make a packet, lay two 24-inch sheets of foil on top of each other (the double layers will help protect the contents from burning); generously coat the top piece with cooking spray. Spread half the potato mixture in the center of the foil in a thin layer. Bring the short ends of foil together, fold over and pinch to seal. Pinch the seams together along the sides to seal the packet. Make a second packet in the same fashion with the remaining potato mixture.
Place the packets on the hottest part of the grill and the pork chops in the front or back. Cook the pork for 3 to 4 minutes per side and the packets for 5 minutes per side. Transfer the chops to plates and let rest while the packets finish cooking. Open the packets (be careful of steam) and serve the pork chops with the vegetables.