01 - Gently muddle the peppermint leaves with lime juice and agave syrup in a sturdy glass or cocktail shaker to release the oils.
02 - Fill two glasses with ice cubes.
03 - Divide the muddled mixture evenly between the prepared glasses.
04 - Top each glass with cold sparkling water and stir gently to combine.
05 - Garnish with lime slices and additional peppermint sprigs as desired. Serve immediately.