Pastrami on Rye: An Overstuffed History of the Jewish Deli. By Ted Merwin. NYU Press; 245 pages; $26.95.

JEWISH delicatessens may now be known for knishes, latkes and pastrami sandwiches, but back in their heyday, during the 1920s and 1930s in the theatre district in New York, they also served beluga caviar, pâté de foie gras and Chateaubriand steak. Jewish classics were gussied up and defiled: chopped chicken liver was served with truffles. Treyf, like oysters and pork chops, was eaten with abandon alongside kosher delicacies.

In his new book “Pastrami on Rye”, one of the first scholarly histories of the Jewish delicatessen, Ted Merwin, a professor of religion and Judaic studies, tracks the rise and fall of delis. The fruit of more than ten years of research and writing, Mr Merwin’s account shows that delis have been a rich part of the story of Jewish assimilation in America.

The first delicatessens sold mostly German food. For early Jewish immigrants, deli meats were an indispensable reminder of home. When kosher beef prices in America jumped from 12 to 18 cents a pound in 1902, riots broke out in Jewish enclaves throughout the north-east. Jewish women boycotted and picketed slaughterhouses, attacked deli customers and set fire to meat they had first doused in petrol. After Orthodox religious leaders endorsed the movement, the price of beef finally began to drop.

Delis were popularised as restaurants by a new generation of American-born Jews. The peak year for European immigration was 1907, with more than 1m newcomers arriving at Ellis Island, the major hub near New York. Over the next three decades the children of these immigrants sought ways of gaining access to the commercial and social life of the city. Jews found an opening at the deli, a place where they could express loyalty to their heritage in a public setting, and where non-Jews could also sample Jewish culture.

To many, deli food came to symbolise Judaism in a secular form. After his Broadway shows Al Jolson, a famous Jewish singer, would invite the whole audience, Jew and gentile alike, to join him at Lindy’s delicatessen. Martin Kalmanoff, a Jewish songwriter, wrote that at the Stage Deli, “You’ll find debutantes with poodles eatin’ hot goulash and noodles.” In 1926 George Jean Nathan, a theatre critic, declared a “sandwich wave”; Jerome Charyn, a New York writer and historian, has referred to the 1920s as the “delicatessen decade”. Jewish culture was suddenly popular culture.

But just as it had started to coalesce, this vibrant world of intermingled classes and races began as suddenly to dissolve. Mr Merwin cites many causes: emigration from cities, concerns about calories and cholesterol, the spread of supermarkets, and a tendency among mid-20th-century Jews to downplay their ethnicity. Mr Merwin writes that there are only 15 proper Jewish delicatessens left in New York—down from about 1,500 in the 1930s.

But in its obsolescence, the delicatessen has also been reconceived. Tourists have been flocking to the original immigrant neighbourhood of the Lower East Side to visit Katz’s Delicatessen, founded in 1888. The Second Avenue Deli has come up with promotional stunts such as sending out deliveries in a horse and buggy. Mr Merwin’s cherished moment of bawdy Jewish-American secularism seems forgotten in this nostalgia for immigrant origins.

At the same time, hip new restaurants are seeking to reinvigorate the deli by serving embellished classics like bone-marrow matzoh-ball soup and chicken-liver terrine with verjus gelé. Such attempts to evoke the past may succeed where they least expect it—delis have been bastardising tradition for a century. But it would be impossible for them to recapture the excitement of Jews’ triumphant entry into American society.