Julienne carrots, leeks, and bell peppers and steam for several minutes.  Drain and rinse vegetables in ice water and set aside.  Preheat oven to 400 degrees.  Butter 4 large rounds of parchment paper.  Distribute half of vegetables on one side of each round of parchment.  Place a salmon filet on the vegetables on each round.  Top the filets with the rest of the vegetables.  Combine white wine and lemon juice and spoon 1 tablespoon on each filet.  Pour melted butter on filets.  Place a thinly-sliced lemon round on each.  Salt and pepper very lightly.  Fold over parchment paper into half circles and roll and crimp edges tightly.  Bake packets at 400 degrees for 10-15 minutes, depending on thickness of the filets.