Add the gin, grape puree, basil syrup and lime juice to a shaker filled with ice.
Shake, and pour into an Old Fashioned glass.
Top with club soda and garnish with Concord grapes and basil leaves.
*Concord grape puree:
1 quart Concord grapes
Puree Concord grapes in a blender. Use a colander to strain out the seeds and skins.
1 cup Sugar
Bunch Thai basil
Heat one cup granulated sugar and one cup water in a pot over medium heat. Stir until the sugar dissolves. Remove the pan from the heat and add Thai basil leaves and stems to the syrup. Let cool, then strain the mixture. Can be refrigerated for up to two weeks in an airtight container.