In a medium bowl, whisk together the soy sauce, grated ginger, honey, minced garlic, sesame oil, and rice vinegar until well combined.
If you prefer a thicker glaze, mix the cornstarch with water in a small bowl to create a slurry, and incorporate it into the marinade.
Place the chicken thighs in a resealable plastic bag or a shallow dish and pour the marinade over them. Seal or cover and marinate in the refrigerator for at least 30 minutes, preferably for 1-2 hours for deeper flavor.
Preheat your grill or a skillet over medium-high heat. Remove the chicken from the marinade, letting the excess drip off.
Grill the chicken thighs for about 6-7 minutes per side, or until they are cooked through and golden brown, brushing with the reserved marinade in the last few minutes of cooking for extra flavor.
Once the chicken is cooked, remove it from the grill and let it rest for a few minutes before slicing.
Garnish with chopped green onions and sesame seeds for added crunch and freshness.