Prep the chicken: Trim off excess fat and any loose pieces on that can burn, then optionally slice in half crosswise for quicker cooking.
Make the marinade by combining all the marinade ingredients until the sugar is dissolved. *Reserve 1/2 cup of the marinade for basting on when grilling.
Marinate the chicken in the marinade either in a shallow baking dish or a Ziplock bag. Make sure all surfaces of the chicken are in contact with the marinade. Cover and refrigerate for 4 to 8 hours, or overnight.
Remove the chicken from the refrigerator 30 minutes before cooking, transfer to a sheet pan or large plate, letting excess marinade drip off.
Preheat the grill for medium-high heat (aim for 400° F) with a two-zone setup.
Clean the grates and brush some canola oil on with tongs and a paper towel to help prevent sticking.
Grill the chicken over the direct heat for about 2 to 4 minutes on the first side, flip to the second side and grill for another 2 to 4 minutes. Then move the thighs over to the indirect heat side of the grill and begin basting on the reserved sauce.
Baste/brush on the remaining sauce an additional 2 to 3 times as it cooks.
Cook until the internal temperature of the thighs reaches 175° F (or 160°F for breasts) using a meat thermometer to verify. The final internal temperature should climb to 180° F for the dark meat and 165° F for white meat as it rests.
Transfer to a serving platter and rest the chicken for 5 minutes before serving. Garnish with sliced scallion and a side of the reserved huli sauce. Enjoy!
Notes
You can use any part of the chicken, or an entire chicken broken down. If cooking bone-in thighs, breasts or larger chicken pieces, then you will definitely want to marinate 8 hours or longer for the best flavor.
Grill in batches (depending on your grill space) Separate the larger and smaller chicken pieces and start grilling the larger pieces first, as they will take longer., then cook the smaller/thinner pieces as they will cook more quickly.
The chicken and the marinade can burn over high heat, so be sure to keep a close eye watching for flare-ups, and move it off the heat if necessary.