01 - Whisk together soy sauce, pineapple juice, brown sugar, ketchup, rice vinegar, ginger, garlic, sesame oil, honey, smoked paprika, and black pepper in a large bowl until the sugar dissolves completely.
02 - Measure out 1/2 cup of the prepared marinade and transfer to a separate container. Cover and refrigerate for later use during grilling.
03 - Place chicken pieces in a large resealable bag or shallow dish. Pour the remaining marinade over the chicken, ensuring each piece is thoroughly coated. Seal or cover and refrigerate for a minimum of 2 hours, preferably overnight for maximum flavor penetration.
04 - Heat grill to medium-high temperature (approximately 400°F). Clean grates thoroughly and brush with oil to prevent chicken from sticking during cooking.
05 - Remove chicken from the marinade and discard the used liquid. Pat the chicken pieces dry with paper towels to promote proper searing and caramelization.
06 - Arrange chicken on the grill skin side down. Cook for 6-8 minutes until the skin develops grill marks and begins to crisp. Flip each piece and continue grilling for an additional 6-8 minutes.
07 - Brush the chicken generously with the reserved marinade. Continue cooking, turning and basting every 2-3 minutes, until the chicken reaches an internal temperature of 165°F and the exterior is caramelized with a sticky glaze, approximately 20-25 minutes total grilling time.
08 - Transfer chicken to a clean platter and allow to rest for 5 minutes, letting the juices redistribute throughout the meat. Garnish with sliced scallions, toasted sesame seeds, and fresh diced pineapple if desired. Serve immediately while hot.