Pack chicken mixture, lettuce, and dipping sauce separately in insulated container with ice packs. To serve, cover bowl of chicken mixture with vented plastic wrap. Microwave on 100% power (high) for 45 to 60 seconds or until heated through, stirring once halfway through cooking. Spoon a rounded 2 tablespoons of the chicken mixture on each lettuce leaf. Roll up and, if desired, cut in half. Serve with dipping sauce.