1. Vegetables should be stir-fried over high heat as quickly as possible to reduce the loss of vitamin C. When stir-fried in oil for three to four minutes, tomatoes retain 94% of their vitamin C, while stir-fried Chinese cabbage for about 15 minutes retains only 57%. To make the stalks easier to cook, you can add a little water and cover the pan to steam them after stir-frying. If cooking whole long leaves, you can make a few cuts at the base.
2. When boiling vegetables, place them in hot water, not cold water. For example, potatoes boiled in hot water lose about 10% of their vitamin C, while those boiled in cold water lose 40%.
3. Always cover the pot when cooking to prevent water-soluble vitamins from escaping with the steam.
4. Avoid blanching vegetables. Some people blanch vegetables in hot water to remove a bitter taste before stir-frying, squeezing out the juice. This causes most of the inorganic salts and vitamins in the vegetables to be lost. If blanching is necessary, try to make use of the blanched water. For example, the water from blanching vegetables for dumplings can be added to the meat filling. This preserves nutrients and makes the filling more flavorful and juicy.
5. When cooking vegetables, adding a starch like water chestnut flour can thicken the soup, making the food more delicious. Additionally, starch contains glutathione, which helps protect vitamins. When cooking meat dishes, adding a little vinegar after the wine can make the dish more fragrant. For vegetarian dishes like bean sprouts, adding a suitable amount of vinegar improves both the taste and nutritional value because vinegar also helps protect vitamins.
6. Wash vegetables before cutting them and avoid soaking them in water. Cut them into larger pieces; the smaller the pieces and the longer the cooking and storage time, the more vitamins and inorganic salts are lost.
7. Try to stir-fry and eat vegetables immediately to avoid keeping them warm for long periods or reheating them multiple times.
8. If a pan fire starts accidentally, throwing a handful of salt into the wok can extinguish it.