If using wooden skewers, soak them in water for at least 30 minutes. Trim excess fat from chicken thighs and cut into 1¼-inch pieces (bite-sized but not too small).

In a medium bowl, whisk together soy sauce, ketchup, brown sugar, pineapple juice, rice vinegar, grated ginger, minced garlic, vegetable oil, liquid smoke, red pepper flakes, kosher salt, and black pepper until sugar is mostly dissolved and mixture is uniform. Reserve 3/4 cup of the sauce in a separate container and refrigerate for later use as finishing glaze (do not use this reserved sauce for basting raw chicken unless boiled first).

Place the chicken pieces in a large resealable bag or nonreactive container and pour the remaining marinade over the chicken. Seal or cover and refrigerate for at least 2 hours and up to 8 hours (overnight okay for deeper flavor).

Assemble skewers

Preheat grill to medium-high (about 375–425°F / 190–220°C). Thread marinated chicken pieces onto skewers, alternating with pineapple chunks, red pepper pieces, and green onion segments to fill each skewer, leaving a little space between pieces so heat circulates evenly. Aim for 3–4 chicken pieces per skewer depending on size, making about 8 skewers total.

Cook

Oil grill grates lightly. Place skewers on the preheated grill and cook for 3–4 minutes per side, turning every 3–4 minutes to achieve even charring and internal temperature. After the first turn (about 4–6 minutes in), brush the exposed chicken with some of the reserved marinade that has been brought to a boil for 1–2 minutes (to make it safe) or use the remaining marinade that cooked in a small saucepan and simmered. Continue grilling and basting once more during the last 2 minutes of cooking. Total cook time should be 10–14 minutes depending on heat and piece size; chicken is done when it reaches 165°F (74°C) internal temperature and edges are caramelized.

Remove skewers from the grill and let rest for 3–5 minutes so juices redistribute. Optionally brush with a little fresh reserved glaze (cooled) before serving.

Pineapple Salsa

While chicken marinates (or up to 1 hour before serving), prepare the salsa. Finely dice the pineapple into small uniform pieces (about 1/4-inch). Finely dice the red onion and mince the jalapeño (remove seeds for milder heat).

Combine diced pineapple, red onion, jalapeño, and chopped cilantro in a medium bowl. Add lime juice, salt, honey (if using), and olive oil. Stir gently to combine and taste; adjust salt or lime juice to preference.

Cover and refrigerate for at least 20 minutes to let flavors meld. Bring to room temperature for 10 minutes before serving with the hot skewers.