1.) Combine onion, lime juice and garlic in a food processor. Process until onion is finely minced. Transfer to a resealable food storage bag. Add cumin, oregano, thyme, and red pepper; knead bag until blended. Place chicken in a bag; press out air and seal. Turn to coat chicken with marinade. Refrigerate 30 minutes or up to 4 hours, turning occasionally.
2.) Spray grid with nonstick cooking spray. Prepare the grill for direct cooking. Remove chicken from marinade. Place chicken on the grid. Grill 5 – 7 minutes on each side over medium heat or until chicken is no longer pink in center. Transfer chicken to a clean serving platter and garnish with cilantro if desired.
Makes 6 Servings (1 grilled chicken breast per serving)