Using a pestle, pound turmeric in a mortar, or alternatively use a grater. Soak extracted juice and pulp in 1 table spoon water, from 3-4 minutes up to a few hours; then strain. Wear gloves to prevent turmeric staining your skin.
In a small bowl, combine strained turmeric powder, 3 tablespoons of fish sauce and pepper. Coat fish pieces with sauce mixture and let stand at room temperature for 20 minutes.
In a medium pot, heat oil over medium heat. Add leek and stir, cover, and cook for 2 minutes. Add tomatoes, remaining 1 tablespoon fish sauce and water, and stir. Cover and reduce heat to low. Cook until tomatoes are just soft, about 5 minutes. Add stock and bring to a boil. Add carambola, fish and its marinade, and half of chilies. Cook, increasing heat to high, until fish is opaque throughout, about 3 minutes for fillets and 5 minutes for steaks. Add bean sprouts, chives with steamed rice and an accompanying plate of soup heabs. Season to taste with fish sauce or nuoc cham sauce.

Serves 4-6

Note: The Vietnamese word “canh” describes a thin vegetable stock, with or without meat/seafood, that is usually served accompanying steamed rice.

3/4 –inch (2-cm) knob fresh turmeric or 2 teaspoons ground turmeric.
4 tablespoon (2 fl oz/60 ml) fish sauce.
1 teaspoon ground pepper.
2 lb (1kg) catfish, cut through the bone into 3/4-inch (2-cm) steaks (cutlets), or about 20 oz (600g) fish fillets.
3 tablespoons vegetable oil
1 large leek or 3 baby leeks, white part only, well rinsed and thinly sliced, or 3 scallions. (shallots/spring onion), including green parts, thinly sliced.
2 small tomatoes, cut into wedges
1 tablespoon water
4 cups (32 fl oz/1 l) chicken stock fish stock or diluted canned chicken broth.
1-2 carambola (star fruits), preferably slightly unripe, coarsely cut
1 fresh long red chili, seeded and thinly sliced length wise.
2 cups (4 oz/125 g) bean sprouts, rinsed and drained.
1/2 bunch Chinese (flat/garlic) chives
1/3 cup (1/2 oz/15g) very coarsely chopped eryngo (saw tooth coriander) leaves or 1 cup (1 1/3 oz/40 g) coarsely chopped cilantro (fresh coriander) sprigs
1/3 cup (1/2 oz/15 g) very coarsely chopped fresh dill
For accompaniments
Steamed Rice

Ingredients

3/4 –inch (2-cm) knob fresh turmeric or 2 teaspoons ground turmeric.
4 tablespoon (2 fl oz/60 ml) fish sauce.
1 teaspoon ground pepper.
2 lb (1kg) catfish, cut through the bone into 3/4-inch (2-cm) steaks (cutlets), or about 20 oz (600g) fish fillets.
3 tablespoons vegetable oil
1 large leek or 3 baby leeks, white part only, well rinsed and thinly sliced, or 3 scallions. (shallots/spring onion), including green parts, thinly sliced.
2 small tomatoes, cut into wedges
1 tablespoon water
4 cups (32 fl oz/1 l) chicken stock fish stock or diluted canned chicken broth.
1-2 carambola (star fruits), preferably slightly unripe, coarsely cut
1 fresh long red chili, seeded and thinly sliced length wise.
2 cups (4 oz/125 g) bean sprouts, rinsed and drained.
1/2 bunch Chinese (flat/garlic) chives
1/3 cup (1/2 oz/15g) very coarsely chopped eryngo (saw tooth coriander) leaves or 1 cup (1 1/3 oz/40 g) coarsely chopped cilantro (fresh coriander) sprigs
1/3 cup (1/2 oz/15 g) very coarsely chopped fresh dill
For accompaniments
Steamed Rice