Cold sauces & condiments
Kasundi
কাসুন্দি · A pungent, tangy Bengali condiment built from ground black and yellow mustard seeds blended with whole spices, green chili, mustard oil, turmeric, and an acidic liquid (vinegar or lemon juice), traditionally matured by fermentation for several days in a sterilized jar. It functions as a reusable base sauce or table condiment rather than a finished plated dish.
The formula
1 cup mustard seed (mixed black + yellow) : ~1 cup total liquid (vinegar/water/oil)
Liquid portion is split among water (for soaking/grinding), vinegar or lemon juice (acid/preservative), and mustard oil (fat/carry).
Identity
- Bengali cuisine
- Eastern Indian / Bangladeshi origin
- Fermented condiment
- Mustard-seed base
- Pungent and tangy flavor profile
- Often compared (but sharper than) English or Dijon mustard
Ingredients
| Base | Black mustard seed | Provides sharp, fiery pungency; typically ~1/3 of total mustard |
| Base | Yellow mustard seed | Milder pungency and bright yellow hue; the larger share of the mustard |
| Acid | Vinegar (white) or lemon juice | Provides tang, slows spoilage, and supports fermentation |
| Liquid | Water | Used to soak seeds and adjust grinding consistency |
| Fat | Mustard oil | Traditional Bengali fat; carries mustard aroma and preserves the paste |
| Aromatics | Green chili | Adds fresh heat and aromatic sharpness |
| Flavor | Turmeric powder | Earthy note and signature golden color |
| Seasoning | Salt | Seasoning and fermentation support |
Method
- 1Rinse and soak black and yellow mustard seeds in water until softened.Hydration softens the hulls so the seeds break down into a smoother paste and release their enzymatic pungency
- 2Dry-roast whole spices (cumin, coriander, ajwain, fenugreek, cardamom, bay, peppercorns, cloves) on low heat until fragrant.Roasting blooms the essential oils and deepens the spice profile without scorching the mustard seeds
- 3Grind the soaked mustard seeds with the roasted spice blend, green chili, salt, and turmeric into a coarse paste, adding water as needed.Coarse grinding preserves texture while fully incorporating aromatics and developing the characteristic pungent bite
- 4Blend in vinegar (or lemon juice) and mustard oil to form a thick, pourable sauce.Acid sets the tangy backbone and oil carries fat-soluble mustard aromas while loosening the paste to serving consistency
- 5Transfer to a sterilized glass jar, seal, and leave at room temperature for several days to ferment.Wild lactic fermentation deepens flavor complexity, softens harshness, and naturally preserves the condiment
- 6Refrigerate after fermentation is judged complete; consume over weeks to months.Cold storage slows further fermentation while keeping the condiment safe and flavorful
Techniques that matter
Dry-roasting whole spices
Releases volatile oils and prevents raw, dusty notes in the finished sauce
Soaking mustard seeds
Softens hulls for grinding and activates the enzymatic reaction that produces pungency
Coarse wet grinding
Builds body and texture while keeping the condiment spoonable rather than smooth like Dijon
Ambient fermentation in sterilized jar
Develops signature tang and complexity while relying on acid + salt + oil as additional safety nets
Variations & derivatives
Aam Kasundi (mango kasundi)Bengal / Bangladesh
Adds grated raw green mango flesh and jaggery/sugar; mustard seeds are soaked and matured with the mango to make a sweet-sour-pungent pickle-style condiment
Instant KasundiModern Bengali home kitchens
Skips long fermentation; relies on extra vinegar/lemon juice and mustard oil for immediate tang and preservative effect
Garlic KasundiBengali
Adds raw garlic cloves to the grind for sharper allium heat
Used in these dishes
Substitutions
- White vinegar → Lemon juice — Citrus gives a brighter, fresher tang but slightly less preservation; safe and common
- Mustard oil → Neutral vegetable oil — Loses signature pungent aroma; not traditional but safe
- Green chili → Dried red chili or chili powder — Changes flavor from fresh-heat to smoky-heat; acceptable but alters character
- Black + yellow mustard mix → 100% yellow mustard seed — Yields milder, less pungent result; closer to Western mustard
Troubleshooting
Kasundi tastes harshly bitter or harsh
Mustard seeds over-roasted or fermentation insufficient; myrosinase not tempered → Allow additional days of fermentation; next batch, soak (don't dry-roast) the mustard seeds
Paste is too thin or runny
Too much water added during grinding, or insufficient mustard seed → Stir in additional soaked-and-ground mustard seed or briefly simmer to reduce
Weak pungency and flat flavor
Old mustard seeds lost potency or fermentation jar not warm enough → Use fresh seeds; keep jar in a warm spot for several days during fermentation
Surface mold or off smell
Jar not properly sterilized or cross-contamination during scooping → Discard and restart with a fully sterilized jar; always use a clean dry spoon