Place basil leaves, honey, and boiling water in a bowl. Use the back of a spoon to bruise the leaves. Cover and allow to steep and cool to room temparture.
Strain the basil/honey mixture into a pitcher and add lemon juice and sparkling water.
To serve, fill glasses with ice and lemon slices. Pour lemonade into glasses and garnish with a lemon slice and basil leaves.
Recipe by Shawn's Plate at http://www.shawnsplate.com/basil-lemonade/