Mustard Oil
Also known as: sarson ka tel, kachi ghani
What Mustard Oil is
Dark amber, sharply pungent, pressed from mustard seed — the cooking fat of Bengal, much of Nepal and the eastern Gangetic plain. Nothing else in the pantry smells like it, and no other oil carries the same back-of-nose bite.
Oil pressed from black and brown mustard seeds; kachi ghani on the label means cold-pressed and unrefined, the grade with the strongest flavour and deepest colour. Its bite is allyl isothiocyanate, the same compound family behind wasabi and horseradish, and it survives pressing intact. Traditional extraction is a wooden or stone press, which is why the good bottles smell loud from across the kitchen.
Taste and texture
Raw, it reaches the nose before the tongue — sharp, mustardy, faintly bitter at the back. Heated to a light smoke and cooled, the traditional first step in Bengali kitchens, much of that edge rounds off into warmth. In a finished dish it reads as a low mustard hum rather than a shout.
Forms to buy
- Kachi ghani (cold-pressed) — The standard amber bottle; for cooking and raw use.
- Refined mustard oil — Milder and lighter; for high-heat frying where the flavour is not the point.
How to cook it
In Bengali and eastern-Nepali kitchens it starts fish curries, fries the panch phoron tempering, and pickles achar as the preserving medium; raw, it is stirred into mashed-potato bhorta, boiled greens, and the tomato-sesame chutney served with momo. When a dish needs its warmth without its bite, heat the oil until it just smokes and let it cool before adding anything else. Treat it as a seasoning oil as much as a frying one — a raw spoonful is often the last step.
Buying note
Typically ¥500–¥900 per litre. One labelling quirk trips people up: some imported bottles carry a 'for external use only' line left over from older regulations elsewhere; Indian grocers in Japan sell cooking-grade bottles for the kitchen, so buy there and check the label reads food-grade.