1. Preheat oven to 400oF. Fold two pieces of parchment paper (24-inches wide) in half and brush inside with olive oil.
  2. Combine carrot, leaks, and celery in a bowl. Add vermouth and toss to coat. Divide vegetables in center of each parchment paper, oil side up, then place salmon over vegetables. Fold the paper over to cover the ingredients. Crimp the paper all the way around to make a tight seal. Transfer packets to a baking sheet and bake 15 minutes. Remove packets from oven to a plate.
  3. Whisk together sour cream, horseradish, and scallions in a small bowl; season with salt and pepper. Serve salmon and vegetables with sauce.
Salmon En Papillote