1. Cook black sugar ginger soup with pandan leaves & set aside.
2. Slice yam & sweet potatoes. Steam until softened.
3. While it's hot, add sugar (3 small sweet potatoes : 3 tbsp sugar) & mashed together with a fork. Then add sweet potato flour & knead until dough don't stick. I don't like to add too much flour & it's gonna stick a little.
4. Roll into balls & place on a floured surface to lightly coat them.
5. Boil until they float. Transfer balls to black ginger soup & it's ready to serve warm or cool.