Prepare the Teriyaki Sauce: In a medium saucepan over medium heat, whisk together 2 tablespoons of cornstarch and ¼ cup of water until smooth. Gradually stir in soy sauce, brown sugar, honey, minced garlic, grated ginger, rice vinegar, and sesame oil. Bring the mixture to a gentle simmer for about 5 minutes, stirring frequently until it thickens to a glossy consistency. Remove from heat and let it cool for later use.

Marinate the Chicken: While the teriyaki sauce cools, cut the chicken into 1-inch cubes. Place the chicken in a ziplock bag and pour in half of the cooled teriyaki sauce. Seal the bag and massage the chicken to ensure even coverage. Let the chicken marinate in the refrigerator for at least 30 minutes.

Skewer the Chicken: Once marinated, take soaked wooden skewers and thread the marinated chicken pieces onto each skewer, leaving space between them for even cooking. Arrange the skewers on a platter.

Grill the Skewers: Preheat the grill to medium heat. Once hot, place the chicken skewers on the grill. Cook for about 20-30 minutes, turning every 3-4 minutes. Ensure chicken reaches an internal temperature of 165°F and baste with reserved teriyaki sauce.

Serve and Garnish: Remove skewers from the grill and transfer to a serving platter. Sprinkle with sliced green onions and sesame seeds before serving.