Begin by preparing the sauce. Mix cornstarch and water in a small bowl until smooth. In a medium saucepan, combine all remaining ingredients, including the cornstarch mixture. Stir continuously while bringing it to a simmer until the sauce darkens and thickens, filling your kitchen with a wonderful smell.

Once thickened, remove the saucepan from heat and cool the sauce entirely. For a quicker option, refrigerate it.

Now, place the cubed chicken into a large ziplock bag and pour half of the cooled sauce over it. Seal the bag and gently shake to ensure the chicken is well-coated. Marinate this in the fridge for at least 30 minutes to allow the flavors to infuse.

Preheat your grill to medium heat. Thread the marinated chicken onto skewers, ensuring they are evenly spaced. The sizzling sound should greet you as you place them on the grill.

Grill the skewers, turning them every 3-4 minutes until the chicken reaches an internal temperature of 165°F, usually about 20-30 minutes. Remember to baste them with the reserved sauce during the last few minutes for extra flavor.

After grilling, take the skewers off the grill and serve them topped with chopped green onions and a sprinkle of sesame seeds, if desired.