The Vesper Martini is a classic cocktail that was first published in Casino Royale, Ian Fleming's 1953 novel about the British spy James Bond. Fleming himself is said to have invented the drink at the famous Duke's Bar in London, England, although his recipe originally called for gin, vodka, and Kina Lillet, a liqueur made with white wine, fruit liqueurs, and quinine. The latter was discontinued in 1986, so Lillet Blanc or Cocchi Americano are now commonly used in its place.
Add gin, vodka, and Lillet Blanc to a mixing glass.
Fill mixing glass with cubed ice.
Using a bar spoon, stir for 30-45 seconds until well-chilled and slightly diluted.
Using a julep strainer, strain into a martini glass.
Garnish with lemon twist.