NEW YORK – Laurence Edelman is not a chef who looks often to Asia for culinary inspiration. 

“I’m not the kind of guy that’s out there looking for the exotic,” said Edelman, who opened his new-American restaurant, Left Bank, this summer in the West Village. But while making his own mustard, he found an enticing ingredient from the East, mustard oil. Edelman now serves this pungent amber oil with lightly pickled mustard seeds on a frisee and cornichon salad with rich pig’s-head terrine. 

“It’s got this clang to it,” he said. “It’s one of those things that once you get that taste of it, then all of a sudden everything is lacking mustard oil.” 

Mustard oil’s silky heat and sinus-clearing vapours will ring a bell for South Asians, particularly in the Bengal region of eastern India and Bangladesh, where it flavours fish curries and mashed vegetable bhartas. It is also used as a massage oil, the only use for which it is legally approved in the United States. 

But more chefs in the United States hunting for new flavours have discovered mustard oil. And while Bengalis mostly use it for sauteeing, which reduces its intensity, US chefs usually finish dishes with a trickle of the sharp raw oil, as Jean-Georges Vongerichten does with blanched mustard greens in his new cookbook, “Home Cooking With Jean-Georges: My Favorite Simple Recipes” (Clarkson Potter). 

Mustard oil is a key ingredient in the “uni panini,” a sandwich with a cult following at Alex Raij’s Chelsea tapas bar, El Quinto Pino. Playing on the Japanese pairing of sea urchin and wasabi, Raij mixes it into butter she slathers on a ficelle and tops with sea urchin. 

“It has these great vapours, but it’s not the kind of heat that lingers,” she said. “I think because it’s an oil, it hits the tongue differently.” 

Ken Oringer said he discovered mustard oil when the Indian cookbook author Madhur Jaffrey made a guest-chef visit to his restaurant, Clio, in Boston. Now he marinates jalapenos in mustard oil for Indian-inspired pickles and poaches fish in mustard oil before searing it with Spanish paprika. 

“There’s no ingredient that comes close to it,” Oringer said. “It brings so much flavour.” 

Few US chefs have featured mustard oil as prominently as Michael Hodgkins, the former chef at Hung Ry, a hand-pulled-noodle shop in Manhattan. In his time there, Hodgkins used mustard oil as his go-to seasoning in everything from a simple salad dressing for shaved apples and local greens to a fried squid dish with fennel and coriander seeds, lime and honey. 

“It doesn’t have that thick, fatty texture that coats your mouth,” he said. “You taste it, and then it’s gone.” 

Koreans use mustard oil in a hot seasoning oil, and some Chinese cuisines employ it in cold dressings. But the most classic Bengali use is in shorshe bata, a powerful paste of mustard seeds and oil that is often used to showcase the delicacy of the shadlike migratory fish ilish. Mohammed Rahman serves it at Neerob, his Bangladeshi restaurant in the Bronx. Although many Bengalis now cook with other oils, Rahman said, traditional dishes aren’t the same without the oil. 

“Back in the days before the British, nobody used vegetable oil or corn oil,” he said. “When you eat it, you feel like you’re eating something.” 

Until recently, good mustard oil was so hard to find in the United States that Bengalis coming here would tuck a can into their suitcases. As the South Asian Diaspora has spread, however, mustard oil imported from India, Bangladesh and Pakistan has become easy to find in specialized stores for around $5 a liter. 

Although it is usually found on shelves of cooking oil, not massage oil, bottles of pure mustard oil sold in the United States must bear a warning: “For external use only.” Since the mid 1990s, the Food and Drug Administration has banned the import or sale of pure mustard oil as a foodstuff. Some mustard oils are 20 percent to 40 percent erucic acid, which studies have indicated might cause heart problems in lab rats. 

But a spokeswoman for the FDA said that as long as bottles bear the warning, the agency doesn’t regulate the oil, and can’t dictate how it is displayed in stores. A spokeswoman for the New York City health department said that if restaurant inspectors saw mustard oil bearing the “external use only” label, they could discard it and issue a violation for having an unapproved food, though she said she has no record of any such violation being issued. 

Despite the rules, erucic acid levels in mustard oil are not necessarily dangerous, said Walter Willet, chairman of the department of nutrition at the Harvard School of Public Health. “The reality is that we are not really sure,” Willet wrote in an email. “The potential hazards are based on animal studies, and to my knowledge we don’t have real evidence of harm to humans.” 

A study in the American Journal of Clinical Nutrition in 2004 found that Indians who ate mustard oil had lower incidences of heart disease, possibly because of its alpha-linolenic acid, an omega-3 fatty acid that is found in plants. 

Though Ramanan Laxminarayan, a research scholar at the Princeton Environmental Institute, said any benefits, like any risks, have yet to be conclusively proved. In any case, Laxminarayan said, he has no concerns about the safety of a drizzle of mustard oil. 

“I can’t imagine that at that quantity of use it could do much of anything at all,” he said. “Just as it would require a lot for serious health benefits, it would probably require a lot for any harm.” Swetal Patel, a vice president at Raja Foods, an importer of the oil, said many South Asian home cooks probably ignore the warning. “They’ve been using it since the day they were born,” he said. Under the brand Swad, his company sells a version blended with vegetable oil that needs no warning. 

For some chefs, the warning is a badge of authenticity. Tom Valenti, chef and owner of Ouest in Manhattan, discovered mustard oil at Kalustyan’s, the international food store. He ignored blended oils without the warning. “I decided to select the one that said ‘for external use only,’ figuring that was the one with the most horsepower,” he recalled. 

He said he now uses a blended oil in his salmon gravlax on a chickpea pancake, drizzled with mustard-oil-steeped caviar. Customers love the dish, Valenti said. “I’ve gotten a couple of, ‘Woo, that’s spicy,’ with slightly watery eyes,” he said. “But there’s always a smile under those watery eyes.”