Step 1

Pierce chicken all over with tip of a small knife; transfer to a large bowl. Purée remaining ingredients and 1/4 cup water in a blender until smooth. Reserve 1 cup for dipping sauce, if desired. Pour remaining marinade over chicken; massage into chicken. (To protect your hands from the chiles' heat, wear latex gloves.) Cover; chill for at least 1 day and up to 2 days.

Step 2

Let chicken sit at room temperature for 1 hour before cooking. Build a medium-low fire in a charcoal grill, or heat a gas grill to medium. Place chicken on grill, skin side up. Cook covered, turning often, until skin is crisp and lightly charred and an instant-read thermometer inserted into the thickest parts of chicken registers 160° (breasts) or 165° (thighs), 30–45 minutes. Transfer to a platter and tent loosely with foil; let stand for 10 minutes. Serve with reserved dipping sauce, if desired.