To absorb more vitamins from vegetables, it is essential to protect them during cooking. Always wash vegetables before cutting them, and do not soak them after cutting, as many vitamins are water-soluble. Some people like to blanch vegetables in hot water before stir-frying, but this causes a significant loss of vitamins. Additionally, avoid overcooking vegetables and refrain from deep-frying them, as vitamin C is very unstable and can be destroyed by prolonged cooking and high heat. Vinegar has a protective effect on vitamins, so you can add a small amount when cooking.
For some vegetables with skins, such as radishes, the outer peel contains significantly more vitamins than the flesh. Be sure not to peel them to avoid unnecessary nutritional loss.