Chop brown onion finely. Mix ingredients for the sauce in a small bowl and set aside.

In a large bowl, put chicken, onion, yolk, ginger, salt and potato starch, and mix very well until very sticky. Divide into 16 pieces and shape like small round or oval hamburger patties.

Heat oil in a frying pan at medium heat, fry patties for 3-4 minutes each side until cooked through. Add the sauce, and cook for a minute coating chicken with the sauce.