Fill a shaker with ice cubes. Add all ingredients. Shake and strain into a cocktail glass. Garnish with lemon.
The drink was invented and named by fictional secret agent James Bond in the 1953 novel Casino Royale. The novel goes on with Bond telling the barman, after taking a long sip, "Excellent ... but if you can get a vodka made with grain instead of potatoes, you will find it still better."