It has a peppery, pungent taste, though the taste is less fiery than mustard greens.
Very young leaves will have a milder taste, and can be used as a salad green. Otherwise, the leaves are cooked, or pickled in brine.
The plant grows about 12 inches (30 cm) tall. It has a base at soil level, out of which grow ribbed stalks with pale green, slightly crinkled leaves.
The plant is highly productive; you can grow up to 26 1/2 pounds of it per square yard (12 kg per square metre.) The strong taste of the leaves is an insect deterrent. Older varieties of the plant tend to bolt in the heat, so they are harvested younger.
Choose ones with crisp, pale green leaves with no yellow areas or holes in them.
You use both the stems and leaves of Gai Choy; just discard the core at the bottom. Cut and chop before washing, then wash well to get rid of sand. A second washing may be necessary.
Dice the stems, and julienne the leaves.
Gai Choy can be cooked up crisp, as in a stir-fry, or slow cooked as in braising, to become really tender. Note that the pungent taste survives slow cooking. When braising it, or adding it to a braised dish, add stem pieces near the start of cooking, holding back on the leaves until the last 20 minutes of cooking.
Blanching the leaves and stems in salted water first can make the taste a bit less pungent.
Mustard greens, rapini
Store in a plastic bag in refrigerator for up to 5 days.
Also transliterated as “Gai Koy” and “Kai choy.”
Ekman, Jenny. Gai Choy fact sheet. Australia: NSW Department of Primary Industries. November 2005.