Persicaria odorata, the Vietnamese coriander, is a herb whose leaves are used in Southeast Asian cooking. Other English names for the herb include Vietnamese mint, Vietnamese cilantro, Cambodian mint, hot mint, and laksa leaf. Its Vietnamese name is rau răm, while in Indonesia, Malaysia and Singapore it is called daun kesum, daun kesom or daun laksa. In Thailand, it is called phak phai (ผักไผ่) and the Hmong word for it is luam laws. In Laos, it is called phak phaew (ຜັກແພວ), and in Cambodia chi krasang tomhom (ជីរក្រសាំងទំហំ) or chi pong tea koun (ជីរពងទាកូន). In North-East India, Manipur state uses this as garnishing herb over various cuisines like eromba and singju. Manipuris called it as Phak-Pai.
It is neither related to the mints, nor is it in the mint family Lamiaceae but the general appearance and odor are reminiscent. Persicaria is in the family Polygonaceae, collectively known as smartweeds or pinkweeds.
Above all, the leaf is identified with Vietnamese cuisine, where it is commonly eaten fresh in salads (including chicken salad) and in raw summer rolls (gỏi cuốn), as well as in some soups such as canh chua and bún thang, and stews, such as fish kho tộ. It is also popularly eaten with hột vịt lộn (fertilized duck egg).
In the cuisine of Cambodia, the leaf is known as chi krasang tomhom (ជីរក្រសាំងទំហំ) and is used in soups, stews, salads, and the Cambodian summer rolls, naem (ណែម).
The Vietnamese coriander is a perennial plant that grows best in tropical and subtropical zones in warm and damp conditions. In advantageous conditions, it can grow up to 15 to 30 cm. In the winter or when the temperature is too high, it can wither.
The top of its leaf is dark green, with chestnut-colored spots while the leaf's bottom is burgundy red. The stem is jointed at each leaf. In Vietnam it can be cultivated or found in the wild. It can grow very well outside in summer in non-tropical Europe. It prefers full sun and well-drained soil. It should be brought inside for winter and treated as a house plant. It rarely flowers outside the tropics, but it is the leaves that have strong culinary use.
C-Methylated homoisoflavanones (3-(4'-methoxy-benzyl)-5,7-dihydroxy-6-methyl-8-methoxy-chroman-4-one, 3-(4'-methoxy-benzyl)-5,7-dihydroxy-6,8-dimethyl-chroman-4-one, 3-(4'-hydroxy-benzyl)-5,7-dihydroxy-6,8-dimethyl-chroman-4-one, 3-(4'-hydroxy-benzyl)-5,7-dihydroxy-6-methyl-8-methoxy-chroman-4-one and 3-(4'-hydroxy-benzyl)-5,7-dihydroxy-6-methyl-chroman-4-one) can be found in the rhizomes of P. odoratum.
Although there are no scientific researches to prove the libido effects but traditionally, in Vietnam Persicaria odorata is believed to repress sexual urges. There is a saying in Vietnamese, "rau răm, giá sống" ("Vietnamese coriander, raw bean sprouts") meaning that Vietnamese coriander has the ability to reduce sexual desires, while bean sprouts have the opposite effect. Many Buddhist monks grow coriander in their private gardens and eat it frequently as a helpful step in their celibate life.
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- Vietnamese Coriander (Persicaria odorata (Lour.) Soják) page from Gernot Katzer's Spice Pages
- Kesom Oil – a New Essential Oil for the International Flavour and Fragrance Industry in First Australian New Crops Conference 1996 – Volume 2
- Heavenly Fragrance: Cooking with Aromatic Asian Herbs, Fruits, Spices and Seasonings, p.29, Carol Selva Rajah, Tuttle Publishing, 2008
- A new C-methylated homoisoflavanone and triterpenoid from the rhizomes of Polygonatum odoratum. Wang D, Li D, Zhu W and Peng P, Natural product research, 2009, 23:6, pages 580-589, PubMed