Grapefruit Mint Paloma Mocktail

Method

1. 1Make the mint syrup. Combine the water and sugar in a small saucepan over medium heat. Stir until the sugar fully dissolves, about 3 minutes. Do not boil. Remove from heat, add the fresh mint leaves, and steep for 15 minutes. Strain through a fine sieve and discard the mint. The syrup keeps in the fridge for 2 to 3 weeks.
2. 2Rim the glasses. Run a grapefruit wedge around the rim of each highball or rocks glass to moisten it. Dip the rim into a shallow plate of coarse salt. For a Mexican-style finish, mix the salt with a little ground chili and dried lime zest, or use Tajin directly. Set aside.
3. 3Mix the base. In a cocktail shaker or tall glass, combine the fresh grapefruit juice, lime juice, mint syrup, and agave syrup. Add a generous handful of ice. Shake or stir vigorously for 15 seconds until the outside of the shaker is cold. The agitation helps the mint syrup integrate and chills the mixture properly.
4. 4Build the drink. Fill the rimmed glasses with fresh ice. Strain the base mixture over the ice. Top slowly with sparkling water, pouring along the side of the glass to preserve the carbonation.
5. 5Garnish and serve. Add a sprig of fresh mint and a thin grapefruit wheel to each glass. Serve immediately — carbonation fades within a few minutes. To batch for a group: multiply the base by the number of servings, mix in a pitcher, refrigerate, and top each glass with sparkling water individually when serving.