Recipe
Canh chua — sour soup with rice paddy herb
- Herb:
- Rice paddy herb Limnophila aromatica
- Method:
- Culinary use
- Plant part:
- Leaf
About 30 minBeginnerRecipe science profile
Procedure
- Dissolve 2 tablespoons of tamarind paste in 1.5 l of water, bring to the boil and add 200 g of pineapple pieces, 2 quartered tomatoes and 1 sliced okra or taro stems.
- Simmer 5 minutes, add 300 g of fish (catfish, pangasius) in pieces and cook 5 minutes more.
- Season with 2 tablespoons fish sauce, a tablespoon of sugar and salt; the soup should be sour, sweet and salty at once.
- In the bowl scatter chopped ngo om, Thai basil and fried garlic; do not cook the herb in the pot.
Extraction
- Herb:
- 1 bunch (about 30 g) of ngò om per 1.5 l of soup
- Solvent:
- add the chopped leaves to the hot soup once it is in the bowl
- Shelf life:
- soup: 2 days in the fridge; add the herb fresh
- Target compounds:
- essential oil containing limonene and perillaldehyde (lemon and caraway) is released by heat; prolonged boiling drives it off
Notes
A southern Vietnamese sour soup with tamarind and pineapple, to which ngo om belongs as surely as salt. No health claims.
Why it works
Ngo om smells somewhere between lemon and cumin: per the analysis by Vairappan et al. 2014 the oil holds mainly limonene and perillaldehyde, monoterpenes released from the leaf by the heat of the soup but driven off by longer boiling — hence the herb goes on in the bowl. Pharmacological data on limnophila (antioxidant, antimicrobial) are laboratory-based; it is a kitchen herb.
Literature
- Vairappan CS et al. (2014): Major volatile hydrocarbons of rice paddy herb, Limnophila aromatica Lam. Merr as possible chemotaxonomic markers. Journal of Tropical Biology and Conservation 11:41–48 — Essential oil composition: limonene, perillaldehyde and other monoterpenes.
Related
Rice paddy herb — Herb card
Culinary use — Processing method detail