Combine butter, 1 tsp lemon zest, minced garlic, salt, and pepper in small bowl. Adjust the oven rack to lower-middle position and preheat the oven to 450 degrees. Cut eight 12-inch sheets of foil; arrange four flat on the counter. Divide the carrot and leek mixture evenly among the four sheets, mounding in center of each. Add salt and pepper to taste.
Pour 1 TBS vermouth or wine 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 one 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 three more times to create a packet about 7 inches square. Place packets on rimmed baking sheet (overlapping slightly if necessary).
Bake packets 15 minutes. Carefully open foil, allowing steam to escape away from you. Using a thin metal spatula, gently slide fish and vegetables onto plate and top with the accumulated juices. Serve immediately, passing lemon wedges separately. 4 servings.
*Haddock, snapper or halibut can be substituted