01 - Whisk together soy sauce, pineapple juice, brown sugar, ketchup, rice vinegar, ginger, garlic, sesame oil, honey, smoked paprika, and pepper in a large bowl until thoroughly combined.
02 - Measure out 1/2 cup of the marinade and set aside separately for basting during grilling.
03 - Place chicken pieces in a large resealable bag or shallow dish. Pour remaining marinade over chicken, ensuring all pieces are evenly coated. Cover and refrigerate for minimum 2 hours, up to overnight for optimal flavor.
04 - Heat grill to medium-high temperature (approximately 400°F). Lightly oil grates to prevent chicken from sticking.
05 - Remove chicken from marinade and discard used liquid. Pat chicken pieces dry with paper towels.
06 - Place chicken skin side down on grill. Cook for 6-8 minutes, then flip and cook another 6-8 minutes.
07 - Brush chicken with reserved marinade. Continue grilling, turning and basting every 2-3 minutes until chicken reaches internal temperature of 165°F and develops caramelized exterior, approximately 20-25 minutes total cooking time.
08 - Remove chicken from grill and allow to rest for 5 minutes. Garnish with scallions, sesame seeds, and fresh pineapple if desired. Serve immediately.