Mix by hand well and form into meatballs. Sauté in 1 tsp oil, remove and reserve.
Heat oil, add garlic and ginger and use to stir fry Napa. Add stock, cover and simmer for 5 minutes. Remove lid and add shiitake, meatballs and oyster sauce. Cover and boil over medium heat a few minutes longer. Add 1 TBS cornstarch blended into 1 tsp water and simmer uncovered to marry ingredients.