Start by preparing the teriyaki sauce: add the cornstarch and water to a bowl and whisk to combine, until it starts to form a slurry.
Next, heat a small saucepan, on the stove, over medium heat, and add the cornstarch mixture to the pan, alongside the brown sugar (or coconut sugar), soy sauce, minced garlic, rice vinegar, ground ginger, honey, and sesame oil.
Bring the sauce to a simmer, then whisk until the sauce lightly thickens.
Once the sauce is done, remove it from the heat and allow it to cool completely. If you want to expedite the process, you can transfer the saucepan to the fridge while you prepare the rest of the recipe.
Prepare the chicken by cutting it into 1" cubes and place them into a bowl.
Next, remove the sauce from the fridge, and add 1/2 of it into the bowl with the chicken, and toss until the chicken cubes are coated in the sauce. Set the other half of the sauce aside.
Allow the chicken to marinate in the sauce for a minimum of 30 minutes, or a maximum of overnight. If letting it marinate for more than 30 minutes, cover the bowl and transfer it to the fridge.
Once the chicken has marinated, place it onto the skewers.
Next, preheat your grill to 350 F.
Once the grill reaches temperature, transfer the skewers to the grill and allow them to cook for 20-30 minutes, or until the internal temperature reaches 165 F. Be sure to rotate the skewers every 3-4 minutes, so that the chicken doesn't burn.
At approximately the 15 minute mark, use the remainder of the teriyaki sauce to baste the chicken.
Once the chicken is done, remove it from the grill.
Garnish with chopped chives and sesame seeds, then serve and enjoy!