Before the story, a practical note: I've assembled the ready-made list of every ingredient you'll need to try this one at home. Onto the tale.
The New York Sour was born in Chicago in the 1870s, but was known at the time as the "Claret Snap" or "Continental Sour." The signature of the drink is the "float" of red wine (traditionally a full-bodied claret) poured gently on top of the sour to create a distinctive dark "cap" that descends into the drink when you sip it.
The name "New York Sour" became dominant around 1906, when bartenders of the city claimed it as their own to ride the growing prestige of New York cocktail culture. The drink survived Prohibition in the American East Coast, where it was often served at the best restaurants of Manhattan. Forgotten for decades, the New York Sour returned with the modern craft cocktail revival, and is today considered one of the most theatrical classic sours.
The best way to honor these historical cocktails is to serve them with the right attention. A complete barman kit on Amazon is the fastest way to get started and make a good impression from day one. And if you want to go deeper and give your house the proper bar vibe, a professional cocktail bar station is the final, definitive touch.