I don't dare to cook too cold soup in autumn and winter. It takes a long time to cook. It won't be too cold. It's important that it happens to be the season of mustard. This soup is very sweet.
Step1:Wash the mustard. Cut it. Peel the sweet potato and cut into large pieces.
Step2:Put all the materials into the pot and add water to the pot. Add more water. Boil the water on a low heat for 23 hours. Add salt.
Cooking tips:There are skills in making delicious dishes.