Mackerel in Fiery Tamarind Coconut Sauce

2 1/2 cups water 6 pieces dried kokum (a sour fruit available at South Asian grocery stores) 1/2 tsp sea salt, plus more to taste 1/2 tsp turmeric 1 lb. mackerel, cut into 2-inch chunks A small, walnut-sized ball of seedless tamarind, about 2 oz. (50 g) 10-15 whole dried red chilies, stemmed (substitute 5 Kashmiri chilies for milder flavour) 6 cloves garlic 1/2 cup frozen grated unsweetened coconut, thawed 1 tbsp sugar 1/2 lemon 1 tbsp chopped fresh coriander for garnish

Combine 1/2 cup water, kokum, salt and turmeric in large mixing bowl. Add fish, cover and refrigerate 1 hour. Lift fish out of marinade, pat dry gently. Discard marinade.

Combine 11/2 cups water and tamarind in measuring cup. Microwave on high 1 minute to soften tamarind. Mash well with fork. Let rest 5 minutes. Place fine sieve over bowl and pour tamarind mixture through sieve, squeezing liquid into bowl. Discard residue in sieve.

Soak dried red chilies and garlic in tamarind water for 2 hours. Pour into blender; add coconut, sugar and remaining 1/2 cup water. Purée to very fine paste.

Scrape paste into cooking skillet. Boil over medium-high heat until starting to bubble. Reduce heat to medium-low and simmer 10 minutes until cooked and slightly thickened, stirring occasionally. Add fish, coat with spice paste. Cover skillet, cook until fish flakes, about 10 minutes. Check for salt, adding more to taste if needed. Transfer to serving platter, squeeze lemon juice over top if desired or cut lemon into thin half slices and use as garnish. Sprinkle chopped fresh coriander.

Serves 2 to 3