The beauty of a foil-pack is that it traps all the juices and flavors of a meal in a tidy bundle. In this recipe, as the shrimps cook, their natural juices combine with butter, white wine and other seasonings to create an abundant pool of broth perfect for dipping crusty bread into.
Preheat a grill to medium. Microwave the potatoes until softened but not fully cooked, about 5 minutes. Let cool a few minutes, then dice.
Put 4 tablespoons butter in a large microwave-safe bowl and microwave until melted. Add the potatoes, corn, garlic and Old Bay and toss well; season lightly with salt and pepper.
Tear off four 18-inch-long sheets of foil. Divide the vegetables among the foil sheets, piling them in the middle. Add the shrimp to the same bowl. Sprinkle with the lemon zest and a pinch of salt and pepper; toss well. Add the shrimp to the vegetable piles.
Drizzle 2 tablespoons wine over each pile of vegetables and shrimp. Cut the remaining 2 tablespoons butter into 4 pieces and add a piece to each pile. Bring the short ends of the foil together and fold twice; fold in the sides to form a packet.
Grill the foil packets until the potatoes are tender and the shrimp is cooked through, 15 to 20 minutes. Remove from the grill and let stand 5 minutes. Carefully open the packets and sprinkle with the parsley; serve with the lemon wedges.