Bok choy is one of the most important Asian greens available. Several varieties of this Brassica, a relative of the cabbage, are grown throughout China, Korea and neighboring countries, where it has been eaten for centuries. It gets its Cantonese name, meaning "white vegetable," from its snow-white stems, which contrast strikingly with its dark green leaves, although many varieties of bok choy are cultivated, and not all share this classic color scheme. Bok choy has a sweet, crisp flavor with just a hint of the mustardy sharpness that characterizes most Brassicas.
Bok choy can be known by many other names. Pak choy is another way of transliterating its Cantonese name; it's also sometimes known as bai cai. In English, the plant is sometimes called Chinese cabbage or Chinese white cabbage, although this name is also often applied to a close relative, napa cabbage. Shanghai bok choy is a particular variety that has pale green leaves and stems instead of the green-and-white combination of other bok choys.
Bok choy has been known by its Chinese name since at least the fifth century, when it was mentioned in a text describing the medicinal values of culinary plants. Archaeological excavations of Banpo village in the Yellow River Valley of China have discovered seeds of a Brassica species that could well be bok choy or one of its close relatives that are over 6,000 years old. This makes it one of the oldest cultivated vegetables in Asia.
Bok Choy and Chinese Medicine
Bok choy is a valuable vegetable in part due to its ease of cultivation and its hardiness in cold weather, not to mention its generous quantities of vitamin A and vitamin C. Traditional Chinese medicine also values it as a medicinal plant, assigning it a "cool" nature and recommending it in particular for ailments of the stomach and large intestine. It is also used to calm a fever and soothe a cough. Its water content can help quench thirst. It can be crushed and applied to minor skin rashes as well.
Introduction to the West
Bok choy was brought to North America by Chinese immigrants in the 19th century; by the 1880s it was being sold in English-language seed catalogs. Nevertheless, it was not well-known in Western kitchens until the 20th century.
Using Bok Choy
Bok choy can be eaten raw, but in Chinese cuisine it is almost always cooked. It can be stir-fried or used in soups. Like chard, you can cook and serve the leaves and the stems separately. Smaller "baby" bok choy bundles, however, are best steamed whole.