In a medium bowl, whisk together soy sauce, honey, brown sugar, rice vinegar, sesame oil, minced garlic, and grated ginger to create the teriyaki marinade.

Reserve 1/3 cup of the marinade in a separate container for basting later.

Add the chicken thigh cubes to the remaining marinade and toss to coat. Cover and refrigerate for at least 30 minutes, or up to 2 hours for maximum flavor.

If using wooden skewers, soak them in water for 20-30 minutes to prevent burning during cooking.

Preheat your grill or grill pan to medium-high heat. Lightly oil the grates to prevent sticking.

While the grill heats, prepare the reserved marinade for basting. In a small saucepan, combine the reserved marinade with the cornstarch and water. Cook over medium heat, whisking constantly, until it thickens into a glaze (about 2-3 minutes). Remove from heat and set aside.

Thread the marinated chicken pieces onto the skewers, leaving a small gap between each piece for even cooking.

Grill the chicken skewers for 4-5 minutes per side, turning occasionally, until the chicken is cooked through and slightly charred. Brush the skewers with the prepared teriyaki glaze during the last minute of cooking for extra flavor.

Remove the skewers from the grill and garnish with sesame seeds and sliced green onions, if desired.

Serve the teriyaki chicken skewers hot with steamed rice or grilled vegetables for a complete meal.