01 - In a large bowl, combine ground chicken, egg, panko breadcrumbs, chopped green onions, soy sauce, mirin, grated ginger, minced garlic, salt, and black pepper. Mix until just combined—do not overwork the mixture to maintain tenderness.
02 - Wet your hands with water to prevent sticking. Form the chicken mixture into 16 evenly sized meatballs, approximately 1.5 inches in diameter.
03 - Heat vegetable oil in a large nonstick skillet over medium heat. Add meatballs and cook for 8–10 minutes, turning occasionally, until browned on all sides and cooked through to an internal temperature of 165°F. Remove from skillet and set aside.
04 - Wipe the skillet clean. In a small bowl, whisk together soy sauce, mirin, sake, sugar, cornstarch, and water until cornstarch is fully dissolved.
05 - Pour the sauce mixture into the skillet and bring to a simmer over medium heat. Stir constantly until the sauce thickens and coats the back of a spoon, about 2 minutes.
06 - Return the cooked meatballs to the skillet. Gently toss to coat evenly in the teriyaki sauce. Simmer for 2–3 minutes to allow the glaze to adhere properly.
07 - Serve hot over steamed white rice. Garnish with sliced green onions and toasted sesame seeds. Alternatively, serve as appetizers with toothpicks.