Preheat your oven to 400°F (200°C) and line a baking sheet with aluminum foil for easy cleanup.
In a medium bowl, whisk together the soy sauce, honey, rice vinegar, sesame oil, minced garlic, and grated ginger until combined.
In a small bowl, mix the cornstarch with water until smooth. Stir this mixture into the teriyaki sauce in the medium bowl.
Pat the chicken drumsticks dry with paper towels. Place the drumsticks in a large bowl or a zip-top bag. Pour half of the teriyaki sauce over the chicken, reserving the other half for later. Toss to coat evenly.
Arrange the coated drumsticks on the prepared baking sheet, making sure they are not touching. Bake in the preheated oven for 30 minutes.
After 30 minutes, remove the drumsticks from the oven. Brush them with the reserved teriyaki sauce, then turn the drumsticks over, and brush the other side as well.
Return the drumsticks to the oven and bake for an additional 15-20 minutes, or until the chicken is cooked through and the skin is caramelized.
Once done, remove from the oven and let them rest for a few minutes before serving.
Sprinkle sliced green onions and sesame seeds on top before serving for added flavor and presentation.
Notes
For extra flavor, marinate the chicken for a few hours or overnight.