Kerala Fish Curry — Kudampuli Sourness and Coconut Technique (केरल मछली करी)

Ingredients

• 700 g firm white fish fillets, such as kingfish, seer fish, or snapper; cut into large pieces
• 4–5 pieces kudampuli (Garcinia cambogia rind), dried, dark brown-black; soaked in 125 ml warm water for 15 minutes before use
• 250 ml thin coconut milk
• 125 ml thick coconut milk, added only in the final 2 minutes
• 2 tbsp Kashmiri red chilli powder, or regular red chilli powder; gives the characteristic red-orange colour
• 2 tbsp coconut oil, or mustard oil in some regional versions
• 1 tsp mustard seeds
• 10–12 fresh curry leaves
• 2 medium shallots, finely sliced
• 1 tsp turmeric, ground
• 1 tsp salt, to taste

Method

1. 1
   Place the kudampuli pieces and their soaking water in a small bowl — soak them long enough that the liquid runs dark amber, which tells you the rind has given up its deep, fruity sourness into the water. Set aside; this souring liquid is added in full with the pieces, so none of that character is lost.
2. 2
   Heat the coconut oil in a manchatti clay pot over medium heat. When the oil shimmers, add the mustard seeds and let them sputter so they release their nutty bitterness into the fat before anything else goes in; add the sliced shallots and curry leaves and cook, stirring, until the shallots are softened and lightly golden at the edges — the pot will smell of toasted coconut oil and fresh curry leaf.
3. 3
   Add the Kashmiri red chilli powder and turmeric to the pot and stir into the shallot base over reduced heat for 30–40 seconds, so the spices fry in the oil rather than steam, which is what turns the fat a deep, uniform red-orange. The colour of the oil at this stage determines the colour of the finished curry.
4. 4
   Pour in the kudampuli pieces with all their soaking liquid and the thin coconut milk, add salt, stir to combine, and bring the sauce to a gentle simmer. This is where the dish lives or dies: taste the sauce now — the sourness should be present, deep and fruity and unlike tamarind; if kudampuli has been replaced with kokum, lemon, or regular tamarind, that defining Malabar character is already gone and the simmering ahead cannot recover it. Adjust salt before the fish goes in, while the sauce is still easy to correct.
5. 5
   Slide the fish pieces carefully into the simmering sauce and do not stir from this point — only shake the pot gently by its handle to distribute the sauce, so the fish holds its form and does not break apart in the acid. Cook, shaking occasionally, until the pieces are just opaque through and offer no resistance when pressed lightly at the thickest point with the back of a spoon.
6. 6
   In the final 2 minutes of cooking, pour the thick coconut milk around the fish pieces rather than directly over them, so it folds into the hot sauce gently without shocking the fish or splitting the milk; shake the pot to incorporate. Remove from heat immediately, as the residual heat held in the clay pot will continue the cooking — the sauce will thicken and turn visibly richer and more opaque as it rests.