Cut off the bottom of the cluster and wash the stalks individually - a lot of sand and grit tend to accumulate at their base. The stalks have a wonderfully crisp texture, and they keep this in a stir fry dish - crunching with watery juiciness. The leaves are slightly bitter, but not overly so, and when added in at the end of cooking, after the stalks are tender, they give a good depth of flavor.
Bok choy is classically used in stir fry - see Barbara's recipe for Bok Choy with Oyster Sauce, Ginger and Fermented Black Beans for a great example and a good recipe. We also like this Bok Choy with Fried Shallots. This Bok Choy Gratin is a more Western use of the vegetable, and it looks very good.
How do you cook with bok choy?
(Image credit: Wegmans)