Serve with your favorite wild-rice blend.
Preheat the oven to 400 degrees. Fold four 18-inch lengths of parchment paper in half crosswise; cut each into a half-heart shape, and open. Place 6 scallops near the crease of each piece. Top each with a quarter of the tomatoes and onion. Drizzle 2 tablespoons wine over each pile. Dot each with 1 tablespoon butter. Season with thyme, salt, and pepper.
Fold the other half of the parchment over the ingredients. Make small overlapping folds to seal the edges, starting at the top of the heart. Two inches from the end, twist the parchment twice, gently but firmly, to seal. Repeat with the other pieces of parchment, making four packets.
Place the packets on a large rimmed baking sheet or in a heavy skillet (preferably cast iron), and bake 20 minutes or until fully puffed. Remove from the oven, and open the packets carefully. Transfer the scallops and vegetables to plates, and spoon some cooking liquid from the packet over them.