1. Combine butter, 1/4 teaspoon zest, 1 teaspoon garlic, thyme, 1/4 teaspoon salt, and 1/8 teaspoon pepper in small bowl. Combine parsley, remaining teaspoon zest, and remaining teaspoon garlic in another small bowl; set aside. Place carrots and leeks in medium bowl, season with salt and pepper, and toss together.

2. Adjust oven rack to lower-middle position and heat oven to 450°F. Cut eight 12-inch sheets of foil; arrange four flat on counter. Divide carrot and leek mixture among foil sheets, mounding in center of each. Pour 1 tablespoon vermouth over each mound of vegetables. Pat fish dry with paper towels; season with salt and pepper and place one fillet on top of each vegetable mound. Spread quarter of butter mixture on top of each fillet. Place second square of foil on top of fish; crimp edges together in 1/2-inch fold, then fold over three more times to create a packet about 7 inches square (see illustrations, above). Place packets on rimmed baking sheet (overlapping slightly if necessary).

3. Bake packets 15 minutes. Carefully open foil, allowing steam to escape away from you. Using thin metal spatula, gently slide fish and vegetables onto plate with any accumulated juices; sprinkle with parsley mixture. Serve immediately, passing lemon wedges separately.

Serves 4