A finely blended mustard flavored oil. A pungent oil pressed from the seeds of the Indian mustard plant Brassica juncea, used both as a cooking medium and a hair and skin beautifying treatment in India. 

Mustard oil, called sarson ka tel in India, has good preserving qualities, so is used for pickles as well as curries. The mustard oil produced in the West is generally milder than the pungent Indian version. Mustard oil is the main cooking oil for centuries in the Eastern and Northern regions of India and in Bangladesh.

Both the Mustard seeds and the Mustard oil have long been used in poultice, plaster, and other external formulation for upper respiratory tract congestion, joint pain, inflammation, and pain in lower back or lumbar region.

Mustard oil is labeled ''For external use only''. There is no need to take that remark seriously, although mustard oil does have cosmetic use in India (e.g. as hair balm). 

In India, it is common to heat mustard oil initially to high temperature, up to the smoking point, and let it then cool down to regular cooking temperature, or even to room temperature, before the cooking proceeds.