Fish Packets with Potatoes, Lemon & Capers

Preheat a gas or charcoal grill. Combine shallots, parsley and capers in a small bowl. Whisk lemon juice, wine, oil and mustard in a small bowl or glass measuring cup. Stack two 20-inch sheets of foil (the double layers will help protect the ingredients on the bottom from burning). Coat the center of the top layer with cooking spray. Arrange one-fourth of the potatoes, slightly overlapping, to form a 5- to 6-inch circle in the center of the foil. Sprinkle with a dash of salt; set a piece of fish on the potatoes. Top with one-fourth of the shallot mixture and 1 tablespoon of the lemon juice mixture. Bring the short ends of the foil together, leaving enough room in the packet for steam to gather and cook the food. Fold the foil over and pinch to seal. Pinch seams together along the sides. Make sure all the seams are tightly sealed to keep steam from escaping. Make 3 more packets with the remaining ingredients. Place the packets on a gas grill over medium heat or on a charcoal grill 4 to 6 inches from medium coals. Cover the grill and cook until the potatoes are tender and the fish is opaque in the center, 8 to 10 minutes, depending on the thickness. (When opening a packet to check for doneness, be careful of steam.) To serve, use a spatula to slide the contents of the packet onto a plate. Top with the remaining lemon juice mixture.