Ker ka Achar

The Marwari desert pickle of ker berries in mustard oil with split mustard seed and fennel

Origin: Jodhpur & Marwar, Rajasthan, India

From the journey of Caper.

The Mediterranean cures its capers in salt and the Thar Desert pickles its own in mustard oil, and the two traditions have never met. Ker is the berry of Capparis decidua, a leafless spiny caper that photosynthesises through its green twigs and fruits in the hottest months when almost nothing else in the desert is producing. Picked green, it is sour, faintly bitter, and hard, and like its Mediterranean cousin it is inedible raw and has to be worked on. Rajasthan's answer is achar: a pickle built on mustard oil, split mustard seed, and the whole-seed masala of the north Indian pickle jar, matured in the sun rather than in a cellar. The method is genuinely a preservation technique and not a flavouring one, and the reasoning behind each step is a desert reasoning. Sun-drying the soaked berries drives off the water that would otherwise spoil the jar. Mustard oil is heated to smoking to kill off its harshness and its microbes. The oil must stand a finger's depth above the pickle at all times, because anything exposed to air will go over. Handled properly the jar keeps for a year and more, which in a region with long dry seasons and no refrigeration was not a nicety but the point. Every Marwari household has a version and the arguments are about the ratios. Some make it with ker alone, some pair it with gunda, the sticky lasoda berry, which is the most common combination sold in Jodhpur markets, and some add unripe green chillies or slivers of raw mango. What nobody varies is the mustard oil and the sun. It is eaten in very small quantities beside dal, bajra roti, and buttermilk, a teaspoon at the edge of the plate, as a sour and salty foil to a diet that is otherwise heavy on pulses and ghee.

Ingredients

Ker

  • 250 g dried ker (Capparis decidua berries)
  • 2 tsp salt, for the soaking water

Pickle

  • 300 ml mustard oil

Masala

  • 3 tbsp split mustard seed (rai kuria or coarsely cracked yellow mustard)
  • 2 tbsp fennel seeds, lightly crushed
  • 1 tbsp fenugreek seeds, coarsely cracked
  • 1 tsp nigella seeds (kalonji)
  • 1 tsp carom seeds (ajwain)
  • 2 tsp Kashmiri red chilli powder
  • 1 tsp ground turmeric
  • 0.5 tsp asafoetida (hing)
  • 3 tbsp salt, or to taste
  • 1 tsp amchur (dried mango powder), optional

Method

  1. Rinse the ker and soak it in plenty of cold water with the 2 tsp of salt for at least eight hours and preferably overnight, changing the water twice.
  2. Drain, rinse, and boil in fresh water for eight to ten minutes until the berries have softened enough to yield to a fingernail but still hold their shape. Drain thoroughly.
  3. Spread the drained ker on a cloth in strong sun for five to six hours, or in an oven at its lowest setting with the door ajar for two hours, until the surfaces are completely dry to the touch.
  4. Heat the mustard oil in a pan until it smokes properly, then take it off the heat and leave it to cool completely to room temperature.
  5. Meanwhile combine the split mustard, fennel, fenugreek, nigella, carom, chilli powder, turmeric, asafoetida, salt, and amchur if using in a large dry bowl.
  6. Add the dried ker to the spice mixture and toss thoroughly with a dry spoon until every berry is coated.
  7. Pour over about two thirds of the cooled mustard oil and mix well, then pack into a sterilised, completely dry glass or ceramic jar, pressing down to remove air pockets.
  8. Pour the remaining oil over the top so it stands at least a finger's depth above the pickle. Cover the mouth with muslin and tie it, rather than sealing with a lid.
  9. Stand the jar in the sun for six to eight days, shaking or stirring with a dry spoon each morning and bringing it indoors at night. Then seal properly and store in a cool dark cupboard.
  10. Leave for a further two weeks before eating. Serve a teaspoon at the edge of the plate beside dal, bajra roti, and buttermilk.

Notes

Dried ker is sold by Rajasthani and North Indian grocers and online, often alongside sangri. Mediterranean capers are a different species entirely and cannot be used: they are already cured, already salted, and far too soft to survive this treatment. The most common Jodhpur version pairs the ker with an equal weight of gunda, the sticky lasoda berry, which needs its seeds removing first. Green chillies split lengthways and slivers of raw mango are both usual additions. Mustard oil sold in some countries is labelled for external use only because of its erucic acid content. Where that applies, cold-pressed rapeseed oil heated the same way is the practical substitute, though the pickle will lack the characteristic pungency. If the surface ever shows fuzzy growth, or the oil smells rancid rather than sharp, discard the jar. A little cloudiness in the oil and sediment at the bottom are normal and expected. The same masala and method work for whole green chillies, for raw mango, and for lime, which is what most Rajasthani households make in the same week from the same bowl of spices.

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