1. Add the lime juice, lemon juice, cilantro, garlic, jalapeño, brown sugar, and salt into a blender. Purée until smooth for about 15 to 20 seconds.
2. Place the chicken in a large pan, at least 11” x 13”. Pour the marinade over the chicken, and turn the pieces to coat. Cover with plastic wrap, and place in the refrigerator for 30 minutes, turning the pieces once after 15 minutes.
3. Heat the grill to about 450°F. Arrange the chicken on the grill, and cook for about 30 to 35 minutes, turning two to three times once it has seared. Cook to an internal temperature of at least 165°F. Serve with lemon and lime wedges.