Sweet Potato Soup

About 5 days ago, I made a sweet potato soup which is a dessert from Hong Kong. Desserts from Hong Kong and China are similar, you can find this dessert in both country. This dessert is part of Tong Sui (sugar water), a Cantonese specialty and are rarely found in other regional cuisines of China. There is a wide variety of Tong Sui in Hong Kong and Malaysia. Usually eaten in Winter.
Here is the recipe of Sweet Potato Soup:

Sweet Potato Dessert (Hong Kong Style)
Ingredients:
1 sweet potato (about 350gm)
3 cups water (cover the sweet potato)
rock sugar (to your taste)
2 to 3 slices of ginger

Method:

1. Bring water to the boil, add ginger into it.

2. Quickly peel sweet potato and cut into small pieces as it turns black easily. Put them into the boiling water and turn to medium heat once the water boils again.

3. Add rock sugar to your taste when the sweet potato turns soft. Serve hot or cold.

I didn't find any difficulties in making this dessert. It's just that no one helps me in recording so it's a bit difficult to do both.