Hot & Sour Fish Soup

Hot and sour fish soup is the Vietnamese (and Southeast Asian) take on a bright, brothy fish soup known there as canh chua. Cod fillets get a quick rub with fish sauce, ginger, and turmeric before poaching in a fragrant lemongrass broth. Lime juice provides the sour, serrano chile delivers the hot, and a finish of cilantro and scallions adds the herbal freshness that defines Southeast Asian cooking.

The pre-cook fish rub is the technique that makes this soup taste of something. Letting the cod stand five minutes in fish sauce, fresh ginger, and turmeric infuses the flesh with flavor before it ever hits the broth. Skip this step and the fish tastes bland against the bold broth.

Lemongrass is the irreplaceable ingredient. The fresh stalks (use only the tender lower bulbs) infuse the simmering water with a citrus-floral note that defines authentic Southeast Asian fish soups. Dried lemongrass works in a pinch but won’t deliver the same brightness. If you can’t find fresh, a few strips of lime zest are a better substitute than dried.

The order of operations is important. Poach the fish in just water and lemongrass first, then remove and add all the flavoring ingredients. Cooking the fish with the acid would toughen it (lime juice essentially cures fish, as in ceviche), so the lime goes in after the fish is done.

Using cod is the recipe’s choice, but any firm white fish works: snapper, grouper, or even tilapia. Avoid flaky soft fish like sole or flounder that fall apart in the broth.

Serve ladled over a mound of jasmine rice in deep bowls.

Chef Tips

• Bruise the lemongrass stalks by smashing them with the side of a knife before simmering, this releases more flavor
• Cut the serrano chile into thin julienne strips for the prettiest color, plus controlled heat
• Use a non-reactive saucepan (stainless or enamel), aluminum reacts badly with the acid
• Add fresh herbs only off the heat to preserve their bright color and flavor

Variations

• Add a half pound of shrimp along with the fish for a richer seafood soup
• Stir in chopped pineapple or tamarind paste for authentic Vietnamese sweetness and sourness
• Top with crispy fried shallots for textural contrast