The foie gras truffle torchon at the Beatrice Inn in Greenwich Village is a decadent indulgence: four discs of silky duck-liver mousse paired with triangles of buttery toast, all arranged on a silver platter. The appetizer goes for $28 — a gateway, perhaps, to the menu’s $375 Porterhouse steak. The restaurant serves about 200 pounds of foie gras a week.

“There’s nothing like it,” said Angie Mar, the restaurant’s chef and owner.

Last October, when the New York City Council passed a ban on foie gras as inhumane, Mayor Bill de Blasio called foie gras “a luxury item that the vast majority of us would never be able to afford.”

“This,” he added, “is not where we should be shedding a tear.”

But two hours northwest of the city, in one of New York’s poorest counties, foie gras plays a much different role. There it is not a luxury splurge but a domino in a fragile local economy. Almost all of the foie gras produced in the United States comes from two duck farms in Sullivan County, where about 400 workers, mostly immigrants from Mexico and Central America, rely on it for their livelihood.