HEAT grill to medium heat.
BLEND dressing and chipotle pepper in blender until smooth. Reserve 1/4 cup for later use.
GRILL chicken, chayotes and onions 25 min. or until chicken is done (165ºF), turning occasionally and brushing with remaining dressing mixture the last 5 min.
CUT chicken in half; place on platter. Toss chayotes, onions and tomatoes with reserved dressing mixture; spoon over chicken. Top with cheese and cilantro.