While the chicken is cooking, prepare the teriyaki sauce. In a small saucepan, combine tamari (or gluten-free soy sauce), water, honey (or maple syrup), rice vinegar, minced garlic, and grated ginger. Bring to a simmer over medium heat. Stir the cornstarch slurry into the saucepan. Continue cooking, stirring constantly, until the sauce thickens, about 2-3 minutes.