Tong sui, also known as tian tang, is a sweet soup or warm custard served as a dessert at the end of a meal in Chinese cuisine. "Tong sui" are loan words taken from the Cantonese term that is applied to these dessert items. As such, the term is generally not used outside of the Cantonese communities.
There is a wide variety of tong sui and in Hong Kong, there are often stalls which devote themselves just to selling different types of desserts. These dessert stalls have also gained prominence in overseas Chinese communities, and can be found in various parts of Canada and the United States.
