Tong sui is a sweet soup that people in some countries in Asia like to eat after a meal, as a dessert or as a snack. It can come in lots of different flavors and colors, and is usually made with sugar, water, and different kinds of ingredients like beans, fruits, or rice flour.
Think of it like when you mix juice with water and pour in some sugar - that's kind of like the base for the soup. Then you might add things like coconut milk or red beans or tapioca pearls or fruit to make it more interesting and flavorful.
Some common types of tong sui include black sesame soup (which is sort of like peanut butter but made with sesame seeds), green bean soup, and red bean soup. Some people believe that certain types of tong sui can be good for your health and help your body feel better after a meal.
Overall, tong sui is like a yummy, sweet soup that you can enjoy as a treat or a dessert, with lots of different ingredients and flavors to choose from!