Prepare campfire or grill for medium heat. Place each fillet, skin side down, on a piece of heavy-duty foil (about 12 in. square). Mix melted butter, basil, lemon juice, salt and pepper; spoon over salmon. Fold foil around fish, sealing tightly.
Cook on campfire or in covered grill until fish just begins to flake easily with a fork, 10-15 minutes. Open foil carefully to allow steam to escape. If desired, serve with lemon wedges.
