What Is Mustard Oil?
Mustard oil is the cold-pressed or expeller-pressed oil extracted from mustard seeds. It is deeply golden-yellow in colour, with a bold, pungent, slightly sharp aroma and flavour that is unlike any other cooking oil. In South Asia — particularly in Nepal, Bengal, Bihar, Assam, Punjab, and Bangladesh — it is not merely a cooking fat but a flavour ingredient in its own right.
In Nepal, mustard oil (888 तेल, tori ko tel) is the traditional cooking oil of the hills, the Terai, and the Newari kitchen. Its sharp, characteristic bite is woven into the identity of Nepali food in a way that no substitute can replicate.
Why Mustard Oil Is Central to Nepali Cooking
1. Flavour That Cannot Be Substituted
Mustard oil has a bold, pungent, slightly bitter sharpness that is deeply embedded in the flavour memory of Nepali cuisine. When you smell a Nepali achar, a Newari choila marinade, or a Nepali momo filling, you are largely smelling mustard oil. Vegetable oil, sunflower oil, or olive oil produce technically similar dishes but with a completely different flavour identity. For authentic Nepali food, there is no substitute.
2. The Raw Oil Technique
One of the most distinctive features of Nepali cooking is the use of raw mustard oil — added unheated directly to marinades, achhars (pickles), and cold preparations. Raw mustard oil has a sharp, almost nose-tingling pungency that heated oil loses. In dishes like Choila, Aloo Achar, and Til Ko Achar, raw mustard oil is the defining flavour. This technique is almost unique to Nepali and Bengali cooking and is what gives these dishes their unmistakable edge.
3. High Smoke Point
Mustard oil has a high smoke point of approximately 250°C — higher than butter, coconut oil, or most vegetable oils. This makes it excellent for high-heat frying and tadka (tarka/tempering). The hot oil blooms spices more effectively than lower smoke-point oils, extracting their fat-soluble flavour compounds quickly and intensely.
4. Traditional and Cultural Significance
In Nepal, mustard oil carries deep cultural weight. It has been used for centuries for cooking, religious rituals, hair oiling, and massage. Mustard fields are a characteristic feature of the Nepali landscape, particularly in the Terai and lower hills. The oil pressed from these fields was the primary cooking fat for generations before refined vegetable oils became widely available. For many Nepali families, the smell of mustard oil is the smell of home.
5. Preservation Properties
Mustard oil’s antimicrobial and antifungal properties make it the oil of choice for pickling and long-preservation achar. Traditional Nepali achhars preserved in mustard oil keep for months without refrigeration. This was critical in mountain communities without reliable refrigeration and remains the traditional method for making long-lasting pickles.
How Mustard Oil Is Used in Nepali Cooking
- Choila marinade: Raw mustard oil rubbed into grilled meat is the signature technique of Newari Choila — the pungency and fat carry all the spices into the meat
- Aloo Achar: Raw mustard oil tossed with boiled potatoes, sesame, and spices gives the characteristic flavour of this beloved Nepali potato salad
- Momo filling: A splash of mustard oil in the momo filling adds characteristic depth and moisture
- Dal tarka: Mustard oil heated until smoking, then poured over dal, gives a Nepali-style tarka its distinctive flavour
- Gundruk ko jhol: Fermented greens soup cooked in mustard oil — the flavours are perfectly matched
- Sekuwa marinade: Mustard oil carries the spices into the meat and creates the characteristic Sekuwa crust on the grill
- Timur ko achar: Raw mustard oil is the medium for timur-based pickles and chutneys
Mustard Oil and the UK — An Important Note
In the UK and EU, mustard oil sold for cooking is technically labelled “for external use only” or “massage oil” due to its erucic acid content, which regulators have flagged in very high quantities. However, mustard oil has been consumed safely across South Asia for thousands of years and continues to be widely used in UK South Asian kitchens. The quantities used in cooking are well within safe consumption levels. Most South Asian grocery stores in the UK stock mustard oil for culinary use, and it is an accepted and traditional part of South Asian cuisine.
Choosing Mustard Oil — What to Look For
- Cold-pressed or kachi ghani: Cold-pressed mustard oil retains more of its natural flavour compounds and pungency. Look for ‘kachi ghani’ on the label — this indicates cold-pressed.
- Golden-yellow colour: Good quality mustard oil is a rich, deep golden-yellow. Pale or watery oil has been over-refined and lacks flavour.
- Bold aroma: Quality mustard oil should have a strong, distinctive smell. Muted or neutral-smelling mustard oil has been refined and is less authentic.
- Reputable brands: P Mark, Patanjali, and other established South Asian brands produce reliable quality mustard oil.
Where to Buy Mustard Oil in the UK
Authentic cold-pressed mustard oil (kachi ghani) is available at MasalaMart — delivered across the UK with free delivery on orders over £50. It’s the essential oil for authentic Nepali and North Indian cooking.