In a mixing bowl, blend the brown sugar, soy sauce, ketchup, pineapple juice, apple cider vinegar, minced garlic, and ginger until thoroughly combined. If you wish, reserve about ⅓ cup of the marinade in an airtight container and refrigerate it for basting later. Keep the remaining marinade aside while you prepare the chicken.

For the chicken, you may trim off any excess fat using kitchen shears, but leaving some fat can enhance the flavor and will render down during grilling. Place the chicken thighs into a large Ziploc bag. Pour the prepared marinade over the chicken, seal the bag securely, and refrigerate for 6-8 hours, allowing the flavors to infuse deeply into the meat.

When you’re ready to grill, preheat your grill to medium-high. Once heated, reduce the temperature slightly, lightly oil the grill grate, and arrange the chicken thighs on the grill. Close the lid and grill the chicken for about 5 minutes on each side, or until an instant-read thermometer registers 165℉ in the thickest part of the meat.

After reaching the desired internal temperature, lower the heat to low and brush each side of the chicken with the reserved marinade, cooking for an additional minute per side to caramelize the glaze.

Once done, remove the chicken from the grill, cover it loosely with foil, and let it rest for approximately 5 minutes before serving to allow the juices to redistribute throughout the meat.