The "overcooked river" is a cooking method in Cantonese cuisine, which means that the food is scalded and cooked to about 70-80%, and then the food is soaked in cold water, so that the nutrients and water of the food are instantly locked in through the effect of thermal expansion and contraction, which is called "overcooked river," a popular expression in Cantonese folklore. The advantage of this is to make the food more refreshing.

Expanded:

When you cook the noodles, it's much more refreshing to pass the noodles through the cold river. When boiling water is used to cook the noodles, the noodles will expand and become soft due to heat. Immediately after entering the cold water, the body of the noodles will contract immediately due to cold, and the heat expansion and contraction will make the body of the noodles tougher as a result, making it more elastic and crisp to eat. If you want to maintain the chewiness, the key is to increase the cooling speed, reduce the time of passing through the cold river, and replace the cold water with ice water for better results.

The cold river can also be the food in the fishy flavor and impurities to the food with cold water or ice water slightly rinsed, and then frying and cooking when the food is more refreshing. For example, pig intestines, people who have eaten pig intestines know that pig intestines are very tough, not easy to bite off. Using a cold river can make the pork sausage a bit crispier.

Baidu Encyclopedia - Cold River