1. Rinse chicken; pat dry with paper towels. Place chicken pieces in resealable plastic bag; set aside.
2. Stir together mustard, vinegar, oil thyme, garlic and red pepper. Pour over chicken; seal bab. Marinate in refrigerator 4 to 24 hours, turning occasionally.
3. Preheat grill for direct cooking. Drain chicken and discard marinade. Place chicken, bone side up, on grill rack. Grill directly over medium heat 25 to 35 minutes or until no longer pink, turning once.
4. Sprinkle chicken with green onion before serving.