Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large mixing bowl, combine ground chicken or turkey, breadcrumbs, chopped green onions, egg, minced garlic, grated ginger, and season with salt and pepper.
Mix all ingredients together until well combined, then form small meatballs about 1 inch in diameter and place them on the prepared baking sheet.
Bake the meatballs in the preheated oven for 20-25 minutes or until cooked through and golden brown.
While the meatballs are baking, prepare the teriyaki glaze. In a small saucepan over medium heat, whisk together soy sauce, honey, rice vinegar, and sesame oil.
Bring the mixture to a gentle boil, then reduce to a simmer. Stir in the cornstarch-water mixture and continue to simmer until the sauce thickens, about 2-3 minutes. Remove from heat.
Once the meatballs are done, remove them from the oven and place them in a serving dish. Pour the teriyaki glaze over the meatballs, tossing gently to coat.
Garnish with sesame seeds and finely chopped green onions before serving.