Combine onion, lime juice and garlic in food processor. Process until onion is finely minced. Transfer to Ziplock bag. Add cumin, oregano, thyme and red pepper; knead bag until blended. Place chicken in bag; press air out and seal. Turn to coat chicken with marinade. Refrigerate 30 minutes or up to 4 hours.
Spray grid with Pam. Prepare grill for direct cooking. Remove chicken from marinade; discard marinade. Place chicken on grid 3-4" from medium hot coals. Grill 5-7 minutes per side our until no longer pink in the center. Garnish with cilantro.