The cover of ‘The Knish War on Rivington Street.’ Photo: Provided.

Once upon a time on New York City’s Lower East Side, Jewish immigrants from Eastern Europe sold knishes from pushcarts and little knisheries. That was more than 100 years ago. But today, those dumplings filled with cheese, kasha or potatoes are still a staple in many delicatessens.

Author Joanne Oppenheim was fascinated with the popularity of those delicious noshes, and wanted kids today to know about them. So, she wrote The Knish War on Rivington Street.

The book’s story, which is based on true events that happened in 1916, is about Benny and his family, who have a successful baked knish business on Rivington Street.

As the story begins, people often wait in line to buy knishes from Benny’s family — and at 5 cents a knish, they’re a real bargain. Then, another family — the Tisch family — opens a store across the street, and starts selling square, fried knishes. A knish war ensues. Prices drop, signs are made, raffles are created, street music is played — anything to sway customers to buy from them.

The mayor comes for a visit, and he can’t decide which kind he likes better — round or square? Baked or fried? Eventually the rivals form a truce, and Rivington Street is called the Knish Capital of the World.

Oppenheim, who was born and raised in New York’s Catskill Mountains, lives in New York City; she got the idea to write the book after she heard a lecture about the history of knishes.

“I was at an event at the Brooklyn Historical Society, and a woman called ‘The Knish Lady’ was talking about the knish war on Rivington Street,” she says. “I went to the archives and read about it in a New York Times article written in January 1916.”

Although her book is very entertaining, her hope is to convey the message that competition is OK — and that you don’t have to be the best, because there is always more than one way to do something. She also wanted to capture pictures of what life was like in the last century — which Jon Davis’ illustrations charmingly achieve.

At the end of her book, Oppenheim added a recipe for knishes. “I mentioned to the editor [that] it would be great to include a recipe — so I had to learn how to make them at home,” she says. “I had to look up recipes and adapt them and make them my own. With beginner’s luck, I think they turned out to be delicious.”

Oppenheim has written more than 50 books for and about kids, including The Prince’s Bedtime and The Prince’s Breakfast. She co-founded, along with her daughter, the Oppenheim Toy Portfolio, where they review children’s products; they have also become contributors on NBC’s Today Show.

According to Oppenheim, when she began writing the book, she knew that kids were more familiar with bagels, but wanted her book to be about a Jewish food perhaps not so widely known. “I wanted kids to understand what a knish was,” she says. “And who knows — maybe knishes will have a rebirth.”