When stir-frying vegetables, many people have done this: to prevent the food from sticking to the wok, they directly add cold water to the steaming hot dish.
Regarding this, Yu Renwen, a senior nutritionist at the General Hospital of the Beijing Military Command, said: This method is not scientific. Because after adding cold water, the temperature in the wok drops suddenly, which prolongs the cooking time of the vegetables. This not only makes the vegetables older, harder, and worse in texture but also causes more nutrients to be lost. If you must add water during stir-frying, it is recommended to add a small amount of boiling water. This way, the cooking temperature will not be affected too much, and the stir-fried vegetables will be relatively crisp and tender.
Yu Renwen suggests that it is best not to add water when stir-frying. Instead, place the cut vegetables directly in the wok to cook, using their own moisture for heat transfer. This is how you make delicious dishes. If you encounter vegetables that are difficult to cook, you can blanch them first. By the time they are seven or eight percent cooked, stir-frying them will make them less likely to stick to the wok.
In addition, when making stewed dishes, especially meat stews, you should add enough water from the beginning. If cold water is added suddenly during the stewing process, the temperature of the broth will change abruptly. This causes the surface of the meat to contract suddenly, making it difficult for the gamey smell to dissipate, the seasonings to penetrate, and the umami of the dish to greatly diminish.