"Create a Filipino-style meatball burger steak with onion gravy and rice. The user already has prepared meatballs, beef stock, basic seasoning, and flour. They do not have Worcestershire sauce or onion powder. Remove breadcrumbs entirely since the meatballs are already prepared. Make the gravy Filipino-style, likely using soy sauce and optional oyster sauce if needed, with sliced onions on top. Use imperial units and include only the ingredients and steps needed for prepared meatballs."