The sour formula is the root of many cocktails, including margaritas and mules, perhaps because it’s so easy to remember and so simple to adapt. All you need:
Shake all ingredients in a cocktail shaker with ice; strain and serve in a martini glass or over ice in an old-fashioned glass. Add club soda and call it a fizz. Or build it in a tall glass with club soda and call it a Collins. Or try these variations:
APRICOT MOSCOW MULE
Fill a copper mug with crushed ice. Add 3 ounces vodka, 1½ ounces Ginger Simple Syrup (recipe, below left), 1½ ounces freshly squeezed lime juice, and half of a thinly sliced apricot. Top with 4 ounces club soda and a squeezed lime wedge. Stir well. Makes 1 (1-cup) cocktail and enough Ginger Simple Syrup for 3 more.
SPICY WATERMELON MARGARITA
Purée 2 cups cubed seedless watermelon in a blender. Wipe the rim of a margarita glass with a lime wedge; dip rim into kosher salt or coarse white decorating sugar. In a cocktail shaker half-filled with ice, add 2 ounces of the watermelon purée, 1½ ounces silver tequila, ¾ ounce Cointreau, ¾ ounce lime juice, and 1 slice jalapeño. Shake until very cold. Strain into prepared glass. Garnish with a watermelon wedge or melon balls and a jalapeño slice—or simply float a jalapeño slice on top of drink. Makes 1 (¾-cup) cocktail and enough watermelon purée for 4 more.
In a cocktail shaker, muddle 5 fresh raspberries and 1 sprig fresh thyme. Add 1½ ounces gin, 1 pasteurized egg white or 1 ounce pasteurized liquid egg whites, ¾ ounce simple syrup, and ¾ ounce fresh lemon juice. Shake until mixture no longer sounds sloshy. (You will feel a lot of pressure.)
Add ice to fill shaker half-full. Shake again until very cold. Strain into a coupe or cocktail glass. Dust top with cinnamon, or garnish with lemon zest curl or additional thyme. Makes 1 (¾-cup) cocktail.