Both brown sugar and rock sugar can be used, depending on your needs. Brown sugar will be more irritating but has higher nutrition. Rock sugar will be less irritating but will not cause irritation. The details are as follows:

Sweet potatoes are a good thing. It contains tannins and oxidases. But these things will turn brown when exposed to iron. Sweet potatoes contain pectin, which is called sweet potato milk. During the heating process, pectin also accelerates the decomposition of starch.

How to cook sweet potato syrup with clear soup and tough potatoes:

Tip 1: Avoid letting sweet potatoes come into contact with iron objects. It is best to use a bamboo knife or stainless steel blade to scrape the skin. Then pry it into potato pieces.

Tip 2: After cutting the sweet potatoes into pieces, soak them in water for about five hours. Change the water frequently during soaking. This will allow the pectin in the sweet potato chunks to dissolve.

Tip 3: After soaking, take out the potato pieces and dry them.

Tip 4: It is best to use an earthenware pot. Heat the bottom of the pot first, then use a little oil to fry a piece of flattened ginger, fry the potato pieces, and add water to cook.

The sweet potato syrup cooked according to these four tips will have pink and tough potato pieces, clear soup color, sweet and smooth taste, and can be eaten hot or cold drink.