Sparkling Cucumber-Basil Limeade

1 cup sugar
1 tablespoon lime zest, plus 1 cup fresh lime juice (4 to 6 limes)
1/4 cup fresh basil leaves, lightly packed
1 medium English cucumber, halved and thinly sliced
2 cups chilled sparkling water

In a small saucepan, bring the sugar, lime zest + 1 cup water to a simmer over medium heat, stirring constantly until the sugar dissolves, about 6 minutes. Remove from the heat + stir in the basil leaves. Let cool for 30 minutes.

Strain the lime/basil syrup through a sieve into a pitcher. Add the cucumber + lime juice; refrigerate for at least 1 hour.  Just before serving, add the sparkling water. Serve over ice.

Adapted from: Everyday with Rachel Ray