Masor Tenga — Assamese Sour Fish Curry (মাছৰ টেঙা)

Ingredients

• 700 g rohu, katla, or catfish, cut into steaks or large pieces
• ½ tsp ground turmeric, divided: half for fish, half for broth
• 3 tbsp mustard oil, for frying
• ¼ tsp fenugreek seeds, a pinch only
• Souring agent — choose one
• 3–4 pieces thekera (dried Garcinia pedunculata), rinsed; substitute kokum outside Assam
• 2 medium tomatoes, roughly chopped; alternative souring agent
• 2–3 segments elephant apple (ou-tenga, Dillenia indica), peeled and broken into pieces; alternative souring agent
• 750 ml water, for the broth; the broth must remain water-thin
• 1 tsp salt, to taste

Method

1. 1
   Rub the fish pieces with half the turmeric and a pinch of salt, so the turmeric begins to draw out surface moisture and its colour penetrates the flesh evenly rather than sitting as a loose powder. Set aside for ten minutes. The flesh should be evenly yellow and feel lightly tacky at the surface.
2. 2
   Heat mustard oil in a wide pan until it just begins to smoke and loses its raw sharpness, because raw mustard oil carries a bitter, acrid edge that would dominate the delicate broth. Fry the fish pieces in a single layer, turning once, until each side is firm and golden, then remove and drain on a rack — the crust must be dry and set. This is where the dish lives or dies: a piece left underfried will dissolve in the thin broth, clouding it and losing all structural integrity.
3. 3
   Reduce the oil in the same pan to a bare film, then add the fenugreek seeds so they fry in concentrated heat rather than swimming in oil, which would make them greasy and slow to release their fragrance. They should splutter and turn a shade darker within seconds, the smell faintly bitter and nutty. Pull the pan from the heat immediately if they darken too fast, as burnt fenugreek will make the whole broth taste harsh.
4. 4
   Add the remaining turmeric to the tadka and stir it through the hot oil for a moment so it blooms and loses its raw, dusty taste before the liquid goes in. Pour in the water, add your chosen souring agent — thekera pieces, chopped tomato, or elephant apple — and bring to a gentle simmer. The broth must remain completely thin and translucent or pale, looking like lightly coloured water, not a sauce.
5. 5
   Simmer the broth for eight to ten minutes so the souring agent has time to release its acid fully into the water rather than leaving it concentrated around the fruit pieces. Taste: the sourness should be clean, refreshing, and light — present but not aggressive. Adjust the salt.
6. 6
   Slide the fried fish pieces into the simmering broth and cook gently for five to seven minutes only, so the crust softens just enough to absorb the sour broth without the flesh breaking down and muddying it. The fish is ready when it is heated through and just beginning to yield at the thickest point when pressed lightly — it must not fall apart. Remove from heat and serve.