“Three measures of Gordon’s, one of vodka, half a measure of Kina Lillet,” says Jelani Johnson, reciting James Bond’s infamous Martini order in Ian Fleming’s Casino Royale. Johnson, former head bartender at Brooklyn’s Gage & Tollner, goes on to emphasize another, less-frequently-cited part of Bond’s quote: “I never have more than one drink before dinner. But I like it to be strong and well made.”

The strength of the Vesper is a key to its appeal, says Johnson, who fine-tuned a version of the hard-hitting Martini during his tenure at Gage & Tollner (he is now assistant distiller at Manhattan’s Great Jones Distillery). “It’s written about a spy ordering a Martini strictly for the sake of it being big and strong,” he explains.

The drink is, at its core, an ultra-dry 8:1 Martini (eight parts spirit—in this case both gin and vodka—to one part vermouth). On its own, that works, says Johnson. But he wanted to find a way to improve it for the classics-oriented Brooklyn bar. “I saw the potential in making the Vesper better than that weird, esoteric James Bond drink, and turning it into Martini for a modern palate.”

Central to this makeover, was recasting the cocktail as a vodka Martini spiked with a splash of gin rather than the other way around. “Vodka is so neutral, it’s a perfect vehicle to add flavor,” he explains. It serves as a lengthener so that nuances from small amounts of supporting ingredients extend throughout the drink. “Vodka is the perfect vehicle to elongate vermouth, and has enough backbone to give it a good push.”

For that vodka base, Johnson selects Absolut, for its “big, creamy mouthfeel” and subtle sweetness. For the gin component, he experimented with a handful of bold, flavorful gins like Monkey 47, Old Raj and Amass, before landing on Tanqueray Ten—its floral and tea-like flavors harmonized best with the drink. What didn’t work was a neutral gin, like Plymouth or Gordon’s, the brand Bond himself specifies.

“It doesn’t work well with soft gins,” Johnson explains. “It needs a robust gin with a ton of flavor that you want to see elongated with vodka.”

Although Kina Lillet—an ingredient lost to time—is called for in Bond’s formula, the modern-day Lillet just didn’t work in Johnson’s Vesper. The quinine in Kina Lillet would have added a desirable “bitterness and robustness” that sweeter Lillet just doens’t provide. “It was a little thin,” he concluded. “The big a-ha moment for me was [using] Cocchi Americano, to make it a little more robust.”

While he prefers a dash of orange bitters alongside the lemon peel garnish for citrusy accent, it’s an optional flourish. Not optional, however, is stirring the drink, instead of shaking it—another Bond-ian specification. “It’s harder to shake a Martini without overdiluting it,” says Johnson; stirring provides more consistent results. At Gage & Tollner, the drink is served in a small V-shaped glass, with the dividend in a small sidecar stashed in ice.

“I took a shine to this drink,” Johnson recalls after trying dozens of Vesper iterations. “I know it’s an unpopular opinion in the realm of bartenders, but I love a vodka Martini.”