Preheat oven to 400°.

Cook leek and carrot in boiling water 1 minute; drain. Combine leek mixture, tarragon, and 1/4 teaspoon salt in a small bowl, tossing gently. Sprinkle salmon evenly with remaining 1/4 teaspoon salt and pepper.

Place 1 phyllo sheet on a large cutting board or work surface (cover the remaining dough to prevent drying); lightly coat with cooking spray. Repeat layers twice, ending with phyllo. Gently press phyllo layers together. Lightly coat top phyllo sheet with cooking spray. Arrange 1/4 cup leek mixture along center of 1 short edge of phyllo, leaving a 4-inch border; top with 1 fillet. Drizzle with 1/2 teaspoon juice. Fold long edges of phyllo over fish.

Starting at short edge with 4-inch border, roll up jelly-roll fashion. Place wrapped fish, seam side down, on a baking sheet coated with cooking spray. Lightly coat wrapped fish with cooking spray. Repeat procedure with remaining phyllo, cooking spray, leek mixture, salmon, and juice.

Bake at 400° for 15 minutes or until lightly browned, and let stand 5 minutes before serving. Serve with lemon wedges.