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
Cuisine bengali, Indian sub-continent


  • 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
Keyword bengali, condiment, fermented, mustard, no-cook, pro-biotic

3 Replies to “Aam Kasundi – Bengali Mustard & Green Mango Relish”

  1. Hello,
    Thank you for this recipe. Though I am from Calcutta, I live in NY and love kasundi, actually all dishes with mustard. I am a ceramic artist and threw a terra cotta container try this recipe. A couple of questions:
    1. The top layer of the mustard keeps drying and forms a reddish cake. Do I need to put extra oil?
    2. Have you made this with olive oil? For some reason in America, FDA doesn’t approve use of mustard oil in foods.
    2. Is it bad to keep peeking into the container and mixing it everyday, or should I leave it undisturbed?

    1. Hi, good to connect with a fellow mustard-lover. I keep my kasundi in a very ordinary jar with tight fitting lid and it just keeps getting better with no skin forming. I also have some home-made miso and have just started some Korean gochujang which I keep in earthenware pots (no plan to share the recipes as I think they’re well covered by others). To prevent that dark layer forming I lay clear plastic film (we call it cling-film in the UK) and pat ii down to form a sort of skin. If plastic isn’t your thing you can try oiled baking parchment. Or, as you said, drop a little oil on top.
      I actually live in Spain (Trujillo, Extremadura) and find that the mustard oil here says for external use only. The guys in the shop (Bangladeshi) assure me they’ve been using it in their cooking for ever with no problem. I certainly haven’t countered any issues, but I never use it when cooking for guests – just in case! Thanks for getting in touch

    2. PS I look at my kasundi admiringly OFTEN. Haven’t noticed any deterioration. But, as a rule of thumb, it’s probably better to leave the thing in peace until fermentation is under way. Regards

Leave a Reply

Your email address will not be published. Required fields are marked *

Recipe Rating