When Lisbon’s Red Frog Speakeasy opened its inconspicuous doors in 2015, it was among the first bars in the city to be built in the neospeakeasy style. Hidden within sister bar Monkey Mash, Red Frog not only serves polished versions of classic cocktails, it also uses culinary-driven techniques to put a modern spin on the menu mainstays.

“The focus of our cocktail program is to reimagine classic cocktails with a gastronomic spin and a touch of Portuguese soul,” says Paulo Gomes, bartender and co-owner at Red Frog, which was recently touted as No. 40 on the World’s 50 Best Bars list. “To execute this concept, we use premium ingredients and manipulate them in our drinks lab using culinary tools and methods to transform familiar classic serves into contemporary ones.”

Guests who manage to find their way into the intimate cocktail bar encounter a range of playful drinks, from a tropical, falernum-laced take on the classic rum cocktail Corn ’n’ Oil, dubbed the Popcorn ’n’ Oil, to more complex serves like the bar’s Zeppelin Funk Punch, a layered milk punch that captures the core of Red Frog’s approach.

“The inspiration behind the Zeppelin Funk Punch is threefold: Led Zeppelin (obviously), London and the 5 o’clock tea ritual,” Gomes explains. “We wanted to create a cocktail that captured the essence of each of these things, and we felt a tea-infused milk punch was the perfect style of drink to do that.”

As is the case with any clarified milk punch, creating the cocktail is a laborious multistep process. (Simply put, milk is curdled with a mixture of liquor and acid—typically citrus—to yield a silky, round and translucent drink that’s full of flavor.) Gomes uses the cocktail format to build a drink that marries notes of ripe berries, gin botanicals, smoke and spice in a way that is precisely integrated and approachable for any drinker.

“We start by infusing gin with a smoked Earl Grey tea from the Azores islands, which we source from a local tea shop called Companhia Portugueza do Chá,” explains Gomes. The smoky, leatherlike flavor is meant to channel the hard edges of rock music, while the tea-infused gin acts as a nod to London’s tradition of afternoon tea as well as the city’s most popular spirit. Ruby port wine gives the milk punch “a sense of provenance,” according to Gomes. In addition to these base notes, Gomes seasons the punch with blueberry syrup, lemon and orange zests and aromatic bitters. For even more depth of flavor, he also incorporates a house five-spice blend and a touch of absinthe. 

To clarify the cocktail, Gomes combines the port wine with buttermilk in one container and mixes the rest of the ingredients in another. “People are always scared of buttermilk,” Gomes says, “but we just say [to guests] that we clarify the cocktail with buttermilk for the velvety texture, and people trust us on it.”  

As the combination of port wine and buttermilk slowly starts to curdle, it’s combined with the remaining ingredients and refrigerated for 48 hours; finally, it’s clarified in a centrifuge.

Though two days is a relatively long period to let a milk punch curdle, Gomes finds that the extra time lets the lactic acidity from the buttermilk shine while also giving the Zeppelin Funk Punch an especially silky texture that makes the cocktail so appealing. 

Finally, “to garnish, we save the curds from the clarification process, dehydrate them and serve them on the side as a way to eliminate waste,” says Gomes. (There aren’t always enough curds to garnish every order of the drink, so some are garnished with an orange coin instead.)

Since its creation in 2017, the Zeppelin Funk Punch has been the bar’s best seller, and Gomes notes that it will continue to be featured on the menu for the foreseeable future. “We have a lot of different customers, from locals who’ve never really drunk these kinds of cocktails to tourists who are serious cocktail lovers,” he says, “and this drink appeals to a wide range of guests.”