Add first 9 ingredients and blend in a food processor for 1 minute or until blended. Place chicken in a shallow baking dish; spoon 3 T cilantro mixture over chicken, turning to coat all sides, reserve remaining cilantro mixture. Cover and marinate chicken at least 4 hours, turning occasionally. Coat grill rack with cooking spray, place on grill over medium-hot coals (350°-400°.) Place chicken on rack and grill 4 minutes on each side or until done (juices from chicken should run clear.) Place a lettuce leaf on each of 2 bread slices. Place chicken breast halves on lettuce, spoon remaining cilantro mixture evenly over chicken, and top with remaining bread slices. Yield: 2 servings.