01 - In a large mixing bowl, combine soy sauce, ketchup, brown sugar, pineapple juice, rice vinegar, grated ginger, minced garlic, sesame oil, Worcestershire sauce, and freshly ground black pepper. Whisk until fully blended.
02 - Measure out 1/3 cup of the prepared marinade and set aside in a separate container for later use as a basting sauce.
03 - Transfer chicken thighs and drumsticks to a large resealable plastic bag or shallow dish. Pour remaining marinade over the chicken, ensuring each piece is thoroughly coated. Seal or cover and refrigerate for a minimum of 4 hours or overnight.
04 - Set grill or grill pan to medium heat, approximately 375°F (190°C).
05 - Remove chicken pieces from the marinade, allowing excess liquid to drip off. Discard used marinade for food safety.
06 - Arrange chicken on grill, skin side down. Grill, turning every 5–7 minutes and basting with reserved marinade, until skin is caramelized and fully cooked, 25–30 minutes. Confirm internal temperature reaches 165°F (74°C).
07 - Transfer cooked chicken to a serving platter. Garnish with thinly sliced green onions and sesame seeds if desired. Serve immediately.