Ker Sangri — Rajasthani Desert Bean and Berry Pickle-Curry (केर सांगरी)

Ingredients

• 150 g ker (Capparis decidua dried berries), small, dusty, greenish-brown; labelled 'ker berry' in Indian grocery stores
• 200 g sangri (dried Prosopis cineraria beans), dried; soaked and boiled separately from ker
• 1 pinch baking soda, divided between two soaking bowls
• 60 ml mustard oil, unrefined; structural to the dish
• 4 dried red chillies, whole
• 1 tsp cumin seeds
• 2 tsp coriander powder
• 2 tsp amchur (dried mango powder), use generously
• 1 tsp salt, to taste

Method

1. 1
   Place ker berries and sangri beans in two separate bowls, cover each generously with cold water, and add a pinch of baking soda to each, so the alkaline water hastens the release of the bitterness and astringency that the desert-drying process locks into both — leave for a minimum of eight hours and the water will visibly darken as those harsh notes leach out. The berries and beans are ready when they have plumped and softened perceptibly to the touch.
2. 2
   Drain and rinse both separately, then place the sangri in a pan of fresh unsalted water and bring to a boil, cooking until approaching tender but still with a slight resistance at the centre — salt at this stage would tighten the skins and slow the softening. In a second pan, boil the ker berries until just yielding; drain both and keep them separate, as the two have different softening times and merging them now would cause one to overcook before the other is ready.
3. 3
   Heat the mustard oil in a wide, heavy pan over a medium-high flame until it begins to smoke lightly and its raw sharpness mellows to a round, pungent heat, so the harsh volatiles that would otherwise sting the back of the throat are driven off and the oil gives the dish its characteristic desert warmth — this is where the dish lives or dies: refined oil or unsmoked mustard oil will produce a generic result that carries none of the character the dish demands. Add the dried red chillies and cumin seeds and let them sputter and colour for thirty seconds.
4. 4
   Add the drained sangri to the pan first, so its denser, starchier flesh has two to three minutes to absorb the spiced oil before the more delicate ker berries join it — stir well to coat every bean. Add the ker berries, then stir through the coriander powder, amchur, and salt; the mixture should sizzle actively with no pooling liquid.
5. 5
   Continue to cook over a medium flame, stirring regularly, until the pan is completely dry — no moisture visible, every piece oil-coated and glossy, the spice powder clinging to the surface of each berry and bean rather than sitting loose in the pan, so the flavours bind to the surface rather than steaming off with evaporating liquid. The amchur's sourness will be present on tasting alongside the residual bitterness of the ker; add no water at any point.