By Priya Krishna
When chef Asma Khan was growing up in Kolkata, India, she learned that there was very little mustard oil couldn’t do. Dry skin? Weak joints? A common cold? A dab of the oil could cure them all.
But she loves cooking with it most: drizzling it into begun pora, a rich and smoky mashed eggplant, or toasting garam masala in it before adding rice and goat to make tehari.
“You feel it coming through your nose,” said Khan, the owner of the Indian restaurant Darjeeling Express in London. “There is a part of it which is really pungent. There is a sweeter side. It is all coming from the mustard oil. It is like a living oil.”
Mustard oil, which is derived from the seeds of the mustard plant, is an everyday ingredient in parts of India and the subcontinent — and is particularly essential in Bengali cooking. In the West, though, it doesn’t have the same visibility.
Because undiluted mustard oil has a high quantity of erucic acid, which has been associated with lipid buildup in the heart based on studies of rats, the European Food Safety Authority recommends consuming mustard oil only in small quantities.
In the United States, the Food and Drug Administration banned most brands of mustard oil for consumption, with many labeled “for external use only,” used by home cooks. (Some brands, such as Carrington Farms, are sold specifically for cooking.)
For Khan and many South Asian cooks, mustard oil is what makes much of their food sing.
“The real taste of the Bengal cuisine comes from the mustard oil,” said Satyen Mazumdar, a former owner of the Indian restaurant Masalawala on the Lower East Side of Manhattan. Mazumdar’s cooking inspired Masalawala & Sons, an eastern Indian restaurant in Park Slope, Brooklyn, owned by his son, Roni, and chef Chintan Pandya.
At Masalawala & Sons, mustard oil weaves its way throughout the menu, awakening the bhetki paturi, fish steamed in a banana leaf, and adding a pleasant sting to the kosha mangsho, lush chunks of braised lamb redolent with warm spices.
In the United States, there is a fledgling movement to change the FDA’s stance on mustard oil. Last year, a group of nutrition specialists published a paper that suggested potential health benefits, like improved insulin resistance, of consuming mustard oil.
Pia Sörensen and Davide Bray, scientists at Harvard University, are exploring how to reduce the erucic acid content in mustard oil. Sörensen said that, to prove whether mustard oil is harmful to eat, tests on humans — rather than rats — tracking the health of participants with different levels of mustard oil consumption are necessary. But these studies can take years.
Roni Mazumdar, of Masalawala & Sons, likened mustard oil to monosodium glutamate, or MSG, a flavor-intensifying chemical compound that can be found in a number of dishes, whether ranch dressing or mapo tofu, and faces stigma in the United States. Just like chefs who have educated diners on why MSG is safe to consume, “we are going to create that same cultural context all over with mustard oil,” Mazumdar said. “We are on that exact same path.”
After all, home cooks and professionals alike prepare dishes with mustard oil all the time.
“Think about it: The largest population in this entire world consumes mustard oil,” said Maneet Chauhan, who runs several restaurants in Nashville, Tennessee, including Chauhan Ale and Masala House. “And the population is not going down, so there has to be something behind that.”
Bengali-Style Mustard Oil Fish
Mustard oil, a key ingredient in many South Asian dishes, is especially important in Bengali cuisine. Its earthy, astringent flavor can bring complexity to a simple cooked vegetable, pickle or tadka. This weeknight dish is inspired by bhetki paturi, a mustard oil-coated fish that gets cooked in a banana leaf. In this recipe, foil is a stand-in for banana leaf (though feel free to use the leaf if you have one!), steaming the fish gently and infusing it with flavor. Coconut and mustard oil are a stellar combination here, as the sweetness of the coconut tempers the bitterness of the mustard oil and seeds. The juices that pool around the cooked fish are especially delicious; be sure to spoon those over the cooked rice.
Yield: 4 servings
Total time: 1 hour
Ingredients:
1 1/2 teaspoons black mustard seeds
1 fresh hot green chile (such as serrano or Thai bird’s eye), finely chopped
2 tablespoons unsweetened grated dried coconut
2 tablespoons finely chopped yellow onion
3/4 teaspoon coarse kosher salt (such as Morton)
1/4 teaspoon ground turmeric
1/4 teaspoon red chile powder (such as cayenne or Kashmiri)
3 teaspoons mustard oil for cooking (see Tip)
1 1/2 pounds cod or haddock, divided into 4 fillets
4 pieces aluminum foil, each large enough to make a loose packet around a fish fillet
Cooked rice, for serving
Preparation:
1. In a large mortar and pestle, coarsely grind the black mustard seeds, then add the fresh chile, coconut and onion, and grind again into a paste. Transfer the paste to a medium bowl and mix in the salt, turmeric, red chile powder and mustard oil until incorporated. (If you don’t have a mortar and pestle, combine the mustard seeds, fresh chile, coconut, onion, salt, turmeric and red chile powder in a mini food processor and pulse until it resembles a paste, then transfer to a medium bowl and stir in the mustard oil until well blended.)
2. To the bowl, add the fish and toss (with clean hands) to evenly coat with the paste. Cover and refrigerate for 30 minutes. Meanwhile, heat the oven to 450 degrees.
3. After the fish is done marinating, place each fillet on one-half of a piece of foil and fold the other half over the fish. Then fold each side over a few times to create a pouch. You should have four pouches. Place the pouches on a baking sheet, and bake for 10 to 15 minutes, depending on the thickness of your fillets. (Carefully open a corner of one packet; the fish should be just opaque throughout.)
4. Remove the baking sheet from the oven, divide the pouches among four plates or shallow bowls and serve with rice. Be sure to spoon the juices from the foil over the top of the fish for extra flavor.
Tip: Mustard oil is available at most South Asian grocery stores. Many will have the label “for external use only,” which some cooks tend to ignore. Some brands (such as Carrington Farms and Yandilla) are sold specifically for cooking and can be purchased in stores or online.