In a small saucepan, whisk together 1 tablespoon of cornstarch and 1 cup of cold water until smooth. Add ½ cup of brown sugar, ½ cup of soy sauce or tamari, ¼ cup of honey, 1 teaspoon of ground ginger, and 1 teaspoon of garlic powder. Bring the mixture to a simmer over medium heat, stirring continuously for about 4 minutes, or until the sauce thickens. Reserve ⅓ cup of this sauce for serving later.

While your teriyaki sauce simmers, pat 2 pounds of boneless, skinless chicken thighs dry with paper towels to remove excess moisture. In a large bowl, season the chicken with 1 teaspoon of kosher salt and toss it with the remaining teriyaki sauce until evenly coated. Allow the chicken to marinate at room temperature for about 15 minutes.

Preheat your grill to high heat, ensuring it's hot enough. Once the grill is around 400°F, carefully oil the grates to prevent sticking.

Transfer the marinated chicken thighs onto the hot grill, allowing excess sauce to drip off. Lower the heat to medium-high and close the grill lid. Grill for about 5 minutes, or until you see nice char marks forming.

After 5 minutes, flip the chicken over and baste it with the reserved teriyaki sauce. Continue grilling with the lid closed for another 7 to 8 minutes, or until the internal temperature reaches 165°F.

Once grilled, remove the chicken from the grill and let it rest for about 5 minutes before serving. Drizzle with the remaining teriyaki sauce and enjoy!