Rich with contrasts, this soup is easy to like. The tamarind and pineapple provide a sweet-and-sour edge, while the okra, tomato, and bean sprouts offer spongy, soft, and crunchy textures. The catfish and cumin ground the dish with their pungent, earthy qualities. If rice paddy herb (rau om) is available, use it for a citrusy accent. Sour fish soups are eaten throughout Southeast Asia. The Viet version often includes sliced taro stems (bac ha), a flavorless ingredient known for its ability to absorb other flavors. I generally omit the stems because they don’t contribute much to the soup, and instead increase the amount of okra, which is added at the end. If you can’t find fresh okra, use frozen whole okra, thawing it and slicing it before you add it to the pan. When fresh or frozen pineapple isn’t around, don’t resort to canned. It is not the same. The soup will be a bit tangier but equally sensational without the pineapple.

　　

Ingredients

serves 4 to 6 with 2 or 3 other dishes

　　1 tablespoon canola or other neutral oil

　　1 small yellow onion, thinly sliced

　　3/4 teaspoon salt

　　1 1/2 teaspoons sugar

　　1 1/2 tablespoons fish sauce

　　1/4 cup Tamarind Liquid (page 319)

　　5 1/2 cups water

　　3/4 pound catfish fillet, cut into 1-inch pieces

　　1 cup bite-sized chunks fresh or frozen pineapple (optional)

　　10 to 12 okra (1/3 pound total), stemmed and cut into 1-inch pieces

　　1/2 pound ripe tomatoes, cored, halved horizontally, seeded, and cut into wedges

　　2 cups bean sprouts (about 1/3 pound)

　　1 teaspoon ground cumin, or 3 tablespoons chopped rice paddy herb

　　5 or 6 sprigs cilantro, coarsely chopped

　　

Step 1

In a 4-quart saucepan, heat the oil over medium heat. Add the onion and cook gently, stirring occasionally, for about 4 minutes, or until fragrant and soft. Add the salt, sugar, fish sauce, tamarind liquid, and water, raise the heat to high, and bring to a boil. Lower the heat to a simmer, add the catfish and pineapple, and simmer for 5 minutes, or until the catfish and pineapple are tender but still firm. If you are not serving the soup right away, turn off the heat and cover.

　　

Step 2

Just before serving, return the soup to a simmer. Drop in the okra and cook for 2 minutes, or until tender but still firm. Add the tomatoes, bean sprouts, and cumin. When the bean sprouts have just wilted, after about 30 seconds, turn off the heat. Taste and add extra salt or fish sauce, if necessary. Ladle into a serving bowl, garnish with the cilantro, and serve immediately.

　　Cooks' Note

　　For sour shrimp soup (canh chua tom), use 3/4 pound medium shrimp, peeled and deveined, instead of the catfish. Also, the pineapple is not optional. You need it for the extra flavor boost it delivers.

　　Reprinted with permission from Into the Vietnamese Kitchen: Treasured Foodways, Modern Flavors by Andrea Nguyen. Published by Ten Speed Press, an imprint of Penguin Random House. Copyright © 2006.  Photographs by Leigh Beisch. Buy the full book from Amazon or Bookshop.