Bok choy is a light, flavorful member of the cabbage family. However, because its leaves aren't as tightly packed as round cabbages, it requires special treatment before you cut it up to use it in your favorite recipe. If you've worked with leeks, you already know that soil and sand can work their way down between the leaves. Bok choy doesn't suffer from this problem quite as badly as leeks, but the process is similar. As long as you're observant, you'll be cooking your bok choy in no time.
Examine the bok choy carefully. If it is tightly packed, it probably will have less dirt inside. If it's more loosely packed, it is probably older and dirtier.
Remove the outer leaves, particularly if they are dirty or disheveled in any way. Discard them in your usual manner.
Cut off the base of the bok choy. The leaves all connect to a base that is attached to the roots of the plant while it is growing. It resembles celery or chicory far more than it resembles round cabbages. It should slice very easily with a sharp chef's knife.
Pull the individual leaves of bok choy apart and rinse them with cold, running water from your faucet. A sprayer-type faucet is very helpful when rinsing vegetables such as this, but it is not necessary if you do not have one.
Examine each leaf as you clean it. Mostly,the leaves inside will be pristine and ready for you to cook after you have cleaned them. However, you may occasionally find a leaf that is past its prime or otherwise looks unfit for your recipe. It is important to weed these out or trim them as necessary before cooking.