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 - Set aside 1/2 cup of the marinade specifically for basting during grilling; keep separate from the marinade used for soaking the chicken.
03 - Place chicken pieces in a large resealable bag or shallow dish. Pour remaining marinade over chicken, ensuring all pieces are thoroughly coated. Cover and refrigerate for minimum 2 hours, up to overnight for maximum flavor penetration.
04 - Heat grill to medium-high temperature (approximately 400°F). Lightly oil the grates to prevent chicken from sticking during cooking.
05 - Remove chicken from marinade and discard the used liquid. Pat chicken pieces dry with paper towels to promote proper searing and caramelization.
06 - Place chicken skin-side down on the grill. Cook for 6-8 minutes until skin begins to crisp and develop grill marks.
07 - Turn chicken pieces and grill for another 6-8 minutes on the second side.
08 - Brush chicken generously with reserved marinade. Continue grilling, turning and basting every 2-3 minutes until thoroughly cooked and caramelized (internal temperature reaches 165°F), approximately 20-25 minutes total grilling time.
09 - Remove chicken from grill and allow to rest for 5 minutes before serving. Garnish with sliced scallions, toasted sesame seeds, and diced pineapple if desired.