In a large mixing bowl, combine water, soy sauce, brown sugar, honey, ginger, and garlic. Whisk until well mixed.

In a small bowl, mix cornstarch and 1/4 cup water until smooth.

Pour the soy sauce mixture into a medium saucepan and cook over medium heat for about 5 minutes.

Once the sauce begins to boil, add the cornstarch mixture and whisk continuously.

When the teriyaki sauce thickens, about 2 minutes, remove from heat and let it cool to room temperature.

Coat the chicken thighs in 3/4 of the teriyaki sauce and marinate in the fridge for at least 1 hour.

Preheat the grill to medium-high heat. Place the chicken thighs on the grill and discard the used marinade. Baste with the reserved teriyaki sauce.

Grill for 5 minutes, then flip and baste with more sauce.

Continue grilling for an additional 5 minutes or until the internal temperature reaches 170°F.

Sprinkle with sesame seeds and serve.