Brassica rapa ssp. parachinensis
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What Is It?
A leafy green member of the diverse Chinese cabbage group. Choy sum, while technically a Chinese cabbage, does not form heads, but instead forms bunches of long, thick stalks. Note that the term choy sum is sometimes applied to other vegetables too (see ‘Need More Detail’ in section below).
YEAR-ROUND; best in cooler months
Green/Sweet/Bitter; generally mild with a slight mustard-green flavour
Chinese flowering cabbage, Chinese mustard, Chinese oil vegetable; yu choy, yau choy (sum) (Cantonese names commonly used in English); yóu cài (xīn), cài xīn (Mandarin). Note that some of these names are used in reference to closely related bok choy as well.
Chinese and pan-Asian grocery stores generally stock Choy Sum.
Look for bright, vibrant greens without obvious yellowing or damaged sections. Smaller stalks are generally milder and more tender.
Difficulty: Easy – Simply wash the greens and remove any damage and, if necessary, the dry cut ends of the stalks. You may want to cook leaves and stalks separately, though this is less of a concern than for vegetables like gai lan.
Can be eaten raw, though far more commonly eaten cooked.
Short Term: Refrigerate
Long Term: Blanch and Freeze
(see ‘Need More Detail?’ below for specifics)
Mild/Sweet/Green – Smaller stalks (choy sum) are generally more tender and mild, while older, larger stalks often have a more pronounced bitter and/or sharp mustard-green flavour.
Plants sold as oil vegetable and edible rape are both closely related and excellent substitutes. Gai lan makes a fairly good substitute, as does bok choy, though both plants differ in terms of texture and cooking requirements.
Yu Choy/Choy Sum is a popular vegetable in a wide variety of Asian (especially Chinese) dishes. It’s often cooked and served as a green side dish, but may also be incorporated into a dish or pickled/preserved.
As a fairly mild green, choy sum can be paired with a very wide variety of ingredients. Ginger, soy sauce, garlic, and other classic Chinese flavourings are popular but by no means the only possibilities.
Size is the biggest factor to consider here, with smaller choy sum (vegetable ‘hearts’) having a milder, sweeter flavour than larger and more sharply mustard-like yu choy. For the record, they’re the same plant, just picked at different ages.
Exceptionally high in Vitamins A & C, and moderately high in calcium
For a full nutritional profile, click Need More Detail? below
The entire above-ground portion of the young plant is eaten, including the leaves and stalks. The small flowers are also edible.
Non-GMO but on ‘contamination watchlists’ (See ‘Need More Detail?’ below)
Health & Science
– Exceptionally healthy and nutrient-dense
– Contains glucosinolates, which are chemical compounds that have demonstrated some cancer-protective benefits at low-to-moderate doses. Exceptionally high doses have been linked to thyroid dysfunction.
Organic vs. Conventional
Both organic and conventionally grown choy sum are commercially available, though organic availability is often very limited regionally. It may be found through some niche retailers, or at farmers markets.