Enter family-owned Russ & Daughters, once merely an "appetising shop" where the smoked salmon and white fish were strictly for taking away, which now has opened a café of its own, and Mile End Sandwich, one of a raft of new entries catering for a generation whose bubbas were too busy pursuing a career to feed them home-made chopped liver.
In London, the demise of Bloom's might have been evidence of the delis' demise on these shores, but multi-layered deli sandwiches are now as big here as they are in New York.
Deli-style pop-up Monty's is serving piled-high pastrami, salt beef and chicken liver layered between slices of home-made rye; a new take on America's beloved grilled cheese sandwich is promised by the Melt Shop, opening soon in Soho; while Daniel Moosah has brought modern deli to Fitzrovia with Delancey & Co.
"Modern" deli? Think flying fish roe and seaweed salad packed into the salmon bagels, and chilli-flavoured cream cheese for the spice addicts whose palates have been honed by the Latin American invasion.
Is this fusion twist on the food of our forefathers a nonsense? Katz's menu may remain unreconstructed, but Russ & Daughters' café offers fish platters enhanced with wasabi-infused roe and horseradish-dill cream cheese, not to mention a shot of vodka to wash down the schmaltz herring.
And although seaweed with your smoked salmon may seem a bit extreme, Moosah is a highly successful gambler, so if he's betting it will go down with today's better-travelled, taste-sensation-seeking young foodies, you'd better believe it.
In fact Moosah launched Delancey & Co with the proceeds of his poker career, he explained over a taste of salted caramel cheesecake - another example of a traditional Jewish dish given a great modern twist.
"I grew up with smoked salmon - my grandfather taught me how to carve it properly," explains the 33-year-old who first flirted with a cooking career after dropping out of a marketing degree following his years at Highgate School.
"I did a year's course at Leith's, but I never wanted to be a chef. Instead, I went into the restaurant property business, and started playing more and more poker."
It became a 10-year career, which Moosah describes as "too lucrative to give up - plus it allowed me to eat in the most amazing restaurants".
But living the Las Vegas dream came to an end soon after Moosah married in 2011. "Round about the time my son Dylan was born, it occurred to me there was a real gap in London for modern deli food served in a setting with funky music and cool artwork."
There's not much space to enjoy the colourful decor in Delancey's (named for its amalgam of his wife, Carly, and son Dylan's names as well as the famous street on Manhattan's Lower East Side), with its handful of stools and a couple of outdoor tables, but Moosah has great plans for expansion, with Manchester or Leeds on the cards as well as Soho and Shoreditch. The sandwiches, sides and cakes are packed to travel, but for those happy to munch their lunch at the counter, there's Prosecco on tap or a range of craft beers to wash it down. The lactose-intolerant who were never catered for by the famously rude waiters at Bloom's and Katz's will be happy to know there's even a dairy-free cream cheese made with tofu.
Will it work? Moosah is convinced today's noshers want a different style of deli to their parents and grandparents: "Nice as it is, why should smoked salmon only be paired with plain cream cheese and an unflavoured bagel? Today's younger generation have been exposed to world cuisines and the notion of fusion. It seems only right that our own traditional Jewish sandwiches are also treated to a modern twist."
And although he admits his sandwiches are aimed primarily at those with adventurous taste buds, he adds: "You'd be amazed at how many old school customers are throwing some seaweed or our signature pink chrain-and-horseradish-flavoured cream cheese into their bagels!"
