Step 1

Preparation Bring lemon juice, sugar, and rosemary to a boil in a small saucepan, stirring until sugar has dissolved, then reduce heat and simmer 2 minutes. Cool completely, about 1 hour. Discard rosemary sprigs.

Step 2

Fill 8 (8-ounces) glasses halfway with ice. Divide syrup (about 2 tablespoons each) among glasses and add vodka (1 tablespoon each). Top off with club soda.