We absolutely adore canh chua ca - Vietnamese sour fish soup - so devoting some of our Saigon trip to learning more about it (and eating a good amount of it) was no hard duty. Read the result in today's Wall Street Journal Asia 'Weekend Journal'.
As sometimes happens, the amount of information the writer wanted to include in her piece exceeded the amount of space alloted the article. This was edited out, but I think it's the most interesting part of the whole thing:
Sour soup is found in many Southeast Asian countries (sinigang in the Philippines, samlass m'chou moan in Cambodia, tomyam in Thailand, sayur asam in Indonesia), suggesting that it may have developed separately in each locale, probably in response to climate. Souring agents such as tamarind, lime juice, and vinegar are believed to possess antibacterial (and other healthful) properties, which would have come in hand in the days before refrigeration, and sour flavors are thought to have a cooling effect on the body. 'It's got zip to it,' says Ms. Nguyen of canh chua ga, and indeed the light, clean, sharp edge that sourness lends dishes is refreshing and energizing in tropically torpid weather. Perhaps most importantly, 'sourness rouses the appetite,' she adds.
The Southeast Asian sour flavor profile accounts quite a lot, I think, for my love for the region's cuisines. When I first lived in Asia almost twenty-five years ago one thing I really had trouble adjusting to was the propensity to eat hot (from heat and, sometimes, spice) foods in steamy weather. I've come around to the view that it's a good, reviving thing to sweat a bit over your meal. If it's a sour and hot dish, so much the better. There really is something about a sour soup that perks you up on a horridly wilting day.
As part of the research for this article we visited with Nguyen Dzoan Cam Van, a lovely woman who is perhaps Vietnam's most well-known food personality. She showed us how to make a fantastic central-style sour soup that's chili hot and soured not with tamarind but with fermented bamboo shoots. Once Ramadan is over and my favorite Malay vendor returns to the market with her freshly fermented bamboo shoots I'll try to recreate it and post it here.