Preheat oven to 350°F.
In a large bowl, combine ground pork, beaten egg, cheese, parsley, salt, and pepper. Mix together until just combined.
In a medium bowl, combine the milk, breadcrumbs, garlic, and onion.
Add milk mixture to the meat mixture being careful not to overwork ingredients.
Form into desired size meatball, greasing hands before starting to keep the meat from sticking, and place in a greased 8x8-inch baking dish.
Place in preheated oven and roast for about 15 minutes (or until the meatballs are crisp on the outside).
While meatballs are cooking, prepare teriyaki sauce.
In a saucepan over medium heat, combine soy sauce, rice vinegar, brown sugar, garlic, and ginger. Whisk ingredients together and cook for 2 minutes or until the brown sugar has dissolved.
Reduce heat to low.
In a small bowl, whisk together cornstarch and water. Pour into the saucepan and simmer until thickened. The sauce should coat the back of a spoon.
Pour the sauce over the cooked meatballs. Cover the dish with foil and return it to the oven to bake for an additional 15 minutes (or until the meatballs are cooked through – 165°F on a meat thermometer).
Garnish with green onions and sesame seeds.