In a large bowl, combine the ground chicken, breadcrumbs, chopped green onions, minced garlic, grated ginger, beaten egg, soy sauce, sesame oil, salt, and pepper. Mix until well combined.
Preheat your oven to 400°F (200°C).
Shape the mixture into small meatballs, about 1 inch in diameter, and place them on a lined baking tray.
Bake the meatballs in the preheated oven for about 15 minutes, or until cooked through and golden on the outside.
While the meatballs are baking, prepare the teriyaki glaze. In a small saucepan, combine the teriyaki sauce and water. Heat over medium heat until it begins to simmer, stirring occasionally.
Once the meatballs are done, remove them from the oven and transfer to the saucepan with the teriyaki glaze. Coat the meatballs evenly, letting them simmer for an additional 2-3 minutes to absorb the flavors.
Serve the teriyaki chicken meatballs warm, garnished with sesame seeds and chopped cilantro.