Eben Freeman of Manhattan’s Tailor explains pumpernickel-raisin Scotch and the mysterious Japanese "hard shake" to F&W’s Nick Fauchald.

The windowed booth overlooking the dining room of Manhattan’s Tailor restaurant looks like the kind of place where a diner would expect to spot a DJ mixing, one hand cupped over his headphones. But the man inside the booth, Eben Freeman, isn’t in charge of the playlist—he’s in charge of the drinks, and the only mixing going on is inside of a cocktail shaker.

Making Freeman a focal point of Tailor seems like an odd choice, given that the restaurant’s chef, Sam Mason, has a following many rock stars would envy. But the booth is the first indication that Tailor approaches cocktails from a new direction. The second is its menu: Freeman’s drinks are as subversive as the salty-sweet, kitchen-lab creations—mustard ice cream, candied olives—that made Mason famous at New York’s temple of molecular gastron­omy, WD-50. A glance at the ingredients on the Tailor cocktail menu confirms this: house-smoked cola, walnut-infused Cognac and dry-hopped gin among them.

Freeman credits Mason as the inspiration behind many of his drinks; he often turns an element of one of the chef’s dishes into a cocktail. Take brown-butter rum, for example. "Sam made some brown butter–rum ice cream, gave me a taste and asked, ’Think you can make this into a drink?’ " Among the bag of tricks Freeman packed for Tailor is a process called "fat washing," an ingenious way to flavor spirits that he borrowed from one of Mason’s desserts. By mixing a melted fat with alcohol, chilling the mix­ture until the fat resolidifies, then skimming it off, Freeman can infuse a spirit without leaving any greasiness behind.

One morning at his Harlem apartment, Freeman demonstrates: He cooks a stick of butter in a saucepan until it turns hazelnut brown, then adds a few glugs of dark rum. The mixture goes into the refrigerator, where it’ll cool for a day or two. He pours out some finished product and offers me a sip: The brown butter flavor is right there, but the rum isn’t the least bit unctuous. "Pick a fat, any fat, and you can infuse it," he says. I pick my favorite: "Bacon fat?" I ask. "Of course," Freeman says. "When I think of pork, my mind goes directly to bourbon," and he pulls a cup of bacon drippings from the refrigerator.

As our bacon-infused bourbon chills, I ask Freeman how far he plans to take the technique. "I want to make a cocktail flavored with Coppertone," he says. "That would be the ultimate summer drink."

Freeman unleashes a few more of his experiments-in-progress: He’s nailed smoked Coke, which involves smoking cola syrup over cherrywood chips. It’s the basis for the Waylon, a campfire-scented spin on a Jack-and-Coke. He’s tinkering with vegetables: Red bell pepper juice adds an earthy complexity to a rum-spiked lemonade he calls Paprika Punch. Then there are the gonzo infusions he displays in apothecary bottles behind Tailor’s bar: Scotch with pumpernickel-raisin bread, bourbon with cigars, vodka with bubble gum (after many trials, Dubble Bubble gum was the winner). He also wants to add a list of "solid cocktails" to the menu—like the gin-and-tonic jellies and the spoonfuls of vodka-and-cranberry "caviar" he made at WD-50. An assortment of cocktail "papers"—like adults-only breath strips—is in the works.

Freeman wasn’t always a liquid magician. Born in New York, he started pouring drinks while studying acting at NYU, then took up bartending full-time when it paid more bills than off-off-Broadway did. During the 1990s, he found himself participating in every bar trend: the microbrew craze, the frozen drinks fad, the Cosmo gold rush. Then, in 1999, he witnessed the gestation of New York’s molecular-gastronomy era while working at Jean-Louis Palladin’s namesake (and short-lived) restaurant, where he befriended the kitchen’s young pastry chef, Sam Mason. Bartenders and cooks have always enjoyed a certain symbiosis, Freeman says: "Chef feeds bartender; bartender gets chef drunk. That’s how Sam and I met."

Also in the kitchen was a sous-chef named Wylie Dufresne, and when Dufresne opened WD-50 in 2003, he put Mason in charge of desserts and hired Freeman to run the bar. And that’s when the career bartender became a molecular mixologist (a title he loathes, but reluctantly accepts). He gained notability among cocktail geeks for inventive, often rebellious drinks that thumbed their noses at New York’s classic-cocktail revival. "Classicists think progressive cocktails are a lark, just like some chefs think molecular gastronomy is a lark," he says. "But now that people are paying $16 for a drink, they want something more than a properly made Negroni. They want to be surprised. They deserve to be surprised."

The morning of my visit, however, Freeman’s latest surprise isn’t found in a glass: It’s in the cocktail shaking itself. Before he’ll show me, he has me do some preliminary research. "Do a Google search for ’hard-shake method,’ " he says. I oblige and am rewarded with a handful of results, all written in secondhand English. What I can extract is this: The hard-shake method is a new way of mixing cocktails, developed by a Japanese bartender named Kazuo Ueda. It’s discussed online with the same language kung-fu buffs use to dissect secret death strikes. When performed correctly, the hard shake yields a drink that’s colder and less diluted than one shaken in the conventional over-the-shoulder manner. Aside from Ueda, I find only one other bartender who has mastered the method, a guy named Stanislav Vadrna, who tends bar in Bratislava, Slovakia (a purported hotbed of mixology). Vadrna, who made a pilgrimage to Tokyo to learn from Ueda, is a friend of Freeman’s and passed on the secret. Freeman has been practicing his hard shake ever since.

"The hard shake is about efficiency," Freeman says one afternoon behind Tailor’s bar, where he’s teaching his new bartenders the technique. He fills a small cobbler shaker (the classic three-piece kind) with vodka and ice, cups his hands around the sides and holds it in front of his chest, his elbows out. He starts by slowly agitating the shaker while bringing it up and down in front of his body, then accelerates; the shaker sounds like a train gaining speed. When he reaches full momentum, the red-faced Freeman looks like he’s performing some kind of ritual dance. He stops and pours the contents into a cocktail glass. The staff leans in, as if the drink were going to speak.

"You can make two identical drinks—one with the hard shake, one without—and serve them side by side," Freeman says. "The hard-shaken one will be colder and more integrated. The other will be less cold—you can measure the temperature with a laser thermometer—more diluted and not as balanced. How can you tell me technique doesn’t matter?"

Will the hard shake change the future of cocktails? "Japanese bartenders are way ahead of American ones in technique," he says. "If we can combine their virtuosity with our love of innovation, we’ll see a big shift in the way we make drinks." And if that doesn’t happen? "I’ve seen every drink fad come and go," Freeman says. "This whole cocktail craze could collapse tomorrow. If it does, that’s fine. I’ll go find a quiet bar and start pouring beers again."