Preheat oven to 400°.
Sprinkle fish with salt and pepper.
Heat a large nonstick skillet coated with cooking spray over medium-high heat. Add leek, fennel, and carrot; sauté 4 minutes or until carrot is crisp-tender. Add broth and soy sauce; cook 3 minutes or until liquid evaporates. Stir in 3 tablespoons chives and 1 tablespoon lemon juice.
Cut 6 (14-inch) squares of parchment paper. Fold each square in half; open each. Place 1 cup vegetable mixture near fold of each paper. Place 1 fish fillet on top of vegetable mixture; top with 1/2 teaspoon chives, 1/2 teaspoon lemon juice, and 2 pieces vanilla bean. Fold paper; seal edges with narrow folds. Place packets on each of 2 baking sheets.
Bake at 400° for 18 minutes or until puffy and lightly browned, rotating baking sheets after 9 minutes. Place on plates, and cut open. Serve immediately.
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