Step 1Combine five of the lime wedges, four of the basil leaves and the simple syrup in a cocktail shaker. Using a muddler or the back of a spoon, muddle firmly five or six times, until the lime wedges have released some of their juice.
Step 2Add the cachaca. Fill with ice and shake until chilled. Strain into a small rocks glass and fill with ice. Top with soda and garnish with the remaining basil leaf and lime wedge.