The rice cooker starts the soup function, (if you use a casserole, use high heat to bring the soup to a boil). When the soup is almost boiling, there will be a lot of floating powder, use a large spoon to skim off the floating powder. Add a small spoonful of vinegar (10ML), cover and simmer for 4 hours. If you are using a casserole, change the heat to the lowest setting and cook for 3-4 hours.