Marinate the chicken: In a medium bowl or 4-cup liquid measuring cup, whisk together the pineapple juice, soy sauce, ketchup, brown sugar, sherry, vinegar, ginger, and garlic. Place the chicken in a large resealable zip-top bag. Pour 2 cups of the marinade over the chicken and seal to close. Reserve the remaining 1 cup marinade for glazing. Place the bag with the chicken on a large plate and refrigerate for at least 2 hours or up to 4 hours.

Preheat the grill: Remove the chicken from the refrigerator 30 minutes before cooking. Preheat a grill to medium (350°F to 400°F). Remove the chicken from the marinade and pat dry with paper towels; discard the bag with the marinade.

Grill the chicken: Brush oil onto the grill grates. Place the chicken on the oiled grates and grill, covered, until grill marks appear, about 3 minutes. Flip the chicken and continue to cook until grill marks appear on the second side, about 3 more minutes. Flip again and continue to cook, flipping every 2 minutes, until an instant-read thermometer inserted into the thickest portion of the thighs registers 135°F, about 4 minutes.

Glaze the chicken: Once the chicken has reached 135°F, brush some of the reserved marinade over the thighs. Cook, flipping and brushing with marinade every 1 to 2 minutes, until glazed and an instant-read thermometer inserted into the thickest portion of the thighs registers 165° to 175°F, 3 to 4 more minutes. Remove from the grill, transfer to a platter, and let rest for 10 minutes.

Grill the pineapple: While the chicken rests, lightly brush additional oil over the grill grates and increase the temperature to medium-high (400°F to 450°F). Place the pineapple slices on the oiled grates and grill, uncovered, until grill marks appear on both sides and the pineapple starts to caramelize, about 4 minutes, flipping once halfway through. Transfer to the platter with chicken. Garnish with scallions, if desired, and serve. Love the recipe? Leave us stars and a comment below!