Oriental mustard greens are very popular in Chinese and Vietnamese cooking and pickling.
The flavour of gai choy is something many people will either love or hate. Large, mature gai choys can be extremely peppery. Mature gai choy needs to be cooked before eating, otherwise it is a bit indigestible. However, baby gai choy can be eaten fresh and is a delicious way to spice up a salad, giving it a hot, mustardy bite. The thick and fleshy stems are often used separately to the more pungent leaves. They can be preserved by salting or pickling in vinegar, or added to a soup. Gai choy stems and leaves can both be used in stir fries, especially if combined with other strongly flavoured ingredients.