Cut off excess fat from chicken thighs and cut each thigh in half or into thirds, depending on the size. Make sure that the chicken pieces are close to the same size.
Add chicken pieces into a large zip-top bag.
Chop an onion into fours, separate the layers, and toss it into the bag with the chicken.
Whisk all ingredients for the teriyaki marinade in a separate bowl and pour it into the bag with the chicken.
Get as much air out of the bag as you can and close it tight. Move the chicken and marinade around to mix it together evenly. Place the bag onto a large plate or into a mixing bowl and into the refrigerator.
Refrigerate it for 4-6 hours.
Grill Chicken Kebabs:
Prepare the charcoal until it's ashed over and add it to the grill. Spread it on half of the grill and leave the other half to be the cooler side. Make sure the grate is clean and let the grill preheat for about 10 minutes. (Set a gas grill to medium-high but leave a cool zone as well.)
Skewer folded chicken pieces alternating with onion slices onto metal or wooden skewers. (If using wooden skewers, make sure to soak them first for about an hour.)
Pour leftover marinade into a small skillet or a metal sauce pan that can go on the grill. (You can also simmer the marinade on the stove if needed.)
Grill chicken kebabs turning them a quarter of the way about every 4 minutes, until chicken is cooked through. If the chicken is searing too fast, move it over to the cooler side of the grill to finish cooking.
Simmer sauce along side of the chicken, over medium-high heat or on the stove. Once sauce is simmered for a minute or two, you can brush it onto the chicken while it’s cooking.
Let cooked chicken rest on the plate for a few minutes before taking it off the skewers and serving.
Disclaimer: Nutrition information shown is not guaranteed to be 100% accurate as most ingredients and brands have a slight variation.