In a large bowl, combine ground chicken or turkey, breadcrumbs, egg, garlic, ginger, green onions, salt, and black pepper. Mix until combined.
Roll the mixture into small meatballs.
Heat a skillet over medium heat and lightly brown the meatballs on all sides.
Transfer the meatballs to the crockpot.
In a bowl, whisk together soy sauce, honey, ketchup, rice vinegar, and sesame oil. Pour the sauce over the meatballs.
Cover and cook on LOW for 3–4 hours or HIGH for 2 hours until the meatballs are fully cooked and tender.
In a small bowl, mix cornstarch and water to create a slurry. Stir it into the crockpot during the last 15 minutes of cooking to thicken the sauce.
Garnish with sesame seeds and sliced green onions before serving.