MIX lime juice and chili powder; pour over chicken in shallow dish. Turn chicken over to coat both sides of each breast. Refrigerate 20 min. to marinate. Remove chicken from marinade; discard marinade.
HEAT barbecue to medium heat. Grill chicken and peppers 5 min. on each side or until chicken is done (170ºF) and peppers are tender.
CUT peppers into thin strips; place in large bowl. Add lettuce and onions; mix lightly. Place on 4 plates. Cut chicken diagonally into thin strips; place on salads. Top with cheese and dressing.