Brassica juncea var. rugosa – another mysterious leaf from the Thai markets

After a delicious Thai lunch at Dokmai Garden I noticed some broad leaves spread out on a teak table. I asked Ketsanee what was going on and she said they are going to pickle ‘phak kiao pri’.

Broad-leaf mustard or swatow mustard (Brassica juncea var. rugosa also known as Brassica juncea subsp. juncea).

This vegetable is not commonly treated in western vegetable or cook books, but a chemical analysis (a bite) will reveal it is a member of the cabbage-wasabi-mustard family (Brassicaceae or Cruciferae) due to the mustard oils. The leaves of this swatow mustard are broad and stiff like iceberg lettuce (Lactuca sativa, a member of the daisy family Asteraceae with a white latex and void of mustard oils). They have prominent white stalks and veins. ‘Pak choi’ (Brassica rapa Chinensis group) may have white veins too, but the leaves are smaller and softer. The original form of Brassica juncea known as ‘leaf mustard’ or ‘Indian mustard’ or ‘Chinese mustard’ has much smaller leaves than variety rugosa aka subspecies juncea.

I find swatow mustard most appealing raw, but Ketsanee remarked that like with the wild spiderflower (which I like raw too) you have to treat these leaves to get rid of the mustard oils:

Buy or grow four heads of swatow mustard. After one or two hours of sun-drying the leaves turn soft. If you can not process the leaves immediately, move the leaves into the shade because they must not turn dry. Squeeze out the sap with your hands (like kneading a dough) and then cover the leaves for 2-3 days in the discarded water used for soaking sticky rice. Add two Chinese spoons of salt (equivalent to 15 ml or one European tablespoon). Ketsanee would add a handful of boiled sticky rice to the pickling jar. Eat with sticky rice and chili dip.

The plant was described by Linnaeus as Sinapis juncea in 1753: “Habitat in Asia”. It was later (1859) transferred to the cabbage genus Brassica by the Russian botanist Vassilii Matveievich Czernajew. The Central Thai name is ‘phakkat khiao pli’, while the similar name mentioned by Ketsanee above is in Esan language.

Text & Photo: Eric Danell