Heat coconut oil in large skillet over medium heat. Add onion, celery, pepper, and garlic. Sauté for 2 to 3 minutes. Add chicken. Sauté for 4 to 5 minutes until brown, stirring frequently. Add bell pepper, mushrooms, and carrots. Sauté for 3 to 4 minutes, stirring frequently. Add rice vinegar, coconut aminos, ground ginger, and crushed red pepper flakes. Stir to coat. Season with sea salt and black pepper. Sauté another 2 to 3 minutes or until the chicken is cooked through. Transfer to a serving platter with lettuce. Spoon 2 tablespoons of chicken mixture into a lettuce leaf, fold over, and enjoy! Serve with beans or cooked rice.