Aam Kasundi – Bengali Mustard & Green Mango Relish

Traditionally served with greens, kasundi ( कसूंदी ) is a perfect accompaniment to dry vegetable snacks such as pakora and samosa. Added to pasta it’s a marriage made in heaven.

Though available commercially, kasundi is easy to make at home. No vinegar or other acids, no additives, no cooking even. Just natural fermentation of raw materials for a condiment bursting with pro-biotic goodness and umami deliciousness.

Kasundi has enjoyed a good bit of of press of late, particularly the variety using tomatoes, often marketed as Indian tomato ketchup. The original (and for me best) is a natural ferment of black and yellow mustard with green mango, green chilli and spices – nothing else, not even tomato.

Bengali fermented mustard and green mango kasandi


naturally fermented mustard seed with green mango - a versatile relish bursting with  umami deliciousness

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Cuisine: bengali, Indian sub-continent
Keyword: bengali, condiment, fermented, mustard, no-cook, pro-biotic


  • 500 g green mango peeled and cut into slices
  • 125 g black mustard of 50:50 black and yellow mustard seeds
  • 1 tsp turmeric powder
  • salt
  • 1 tsp sugar (optional)


  • clay pot for fermentation unglazed on the inside
  • glass jar with lid for storage


Remove bitterness from the mustard (3-7 days) - this step can be omitted

  • Wash the mustard seeds and strain off the water. Lay them out on a wide shallow dish and expose them to direct sunlight for 3 - 7 days. Avoid further contact with water. The seeds must be quite dry before proceeding

Salt the mangoes to extract liquid (overnight) - this step can also be omitted

  • peel the green mangoes and cut them into slices or chunks, discarding the skin and stone
  • Place the mangoes in a colander or strainer and sprinkle with enough salt to cover all surfaces. Leave overnight over a bowl to collect the juices. Avoid exposure to bright sunlight as this may discolour the mangoes

Prepare the Kasundi

  • Grind the mustard to a fine powder in an electric spice or coffee grinder
  • Discard the mango juices and squeeze the mango pieces to extract as much joiuce as you can. Discard this also.
  • Lay the mango pieces on a chopping board and pound them with a pestle to roughly break them up
  • Add the mustard, turmeric and sugar if using it plus extra salt to taste
  • Knead the mixture by hand as you would for bread dough for a few minutes.  It's a good idea to wear food gloves for this step.
  • Finally add a good glug of mustard or other vegetable oil and mix in with a spoon
  • Place the mixture in a clay pot with a loose fitting lid. The clay will absorb any excess moisture and help guarantee the mixture won't rot before fermenting. Covver the whole thing with muslin and leave at room temperature for about a week
  • Transfer to a clean glass jar with a tight fitting lid. Store in the fridge for up to three months, during which time it will improve


The oldest recipes use neither garlic, ginger or chilli and turmeric is the only spice used.
Many cooks will add garlic and ginger paste and finely chopped or ground green chillies.
I've sometimes included a couple of teaspoons coriander powder and one of cumin with good results.
It depends how much of a purist you are. I like to experiment, but at the same time like clean simple flavours and have personally setttled on the given recipe. Play around. Find your personal favourite

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