Vegetables should be washed before cutting, otherwise water-soluble vitamins and minerals will be lost. When cutting vegetables, it is generally not advisable to chop them too finely; if they can be torn by hand, do so, and use a knife as little as possible, because iron can accelerate the oxidation of vitamin C.
When stir-frying, use high heat and cook quickly, avoid long stewing, and keep the lid on the pot to prevent water-soluble vitamins from escaping with the steam.
When stir-frying, use as little water as possible. When stewing, add a little vinegar appropriately, which can not only season the dish but also protect the vitamin C from loss. When cooking meat dishes, adding a little starch appropriately can reduce the loss of nutrients and improve the texture.