To make the peach blueberry puree, add peach and blueberries to a blender. Puree until smooth.
To make the margarita, shake peach blueberry puree, tequila, lime juice and agave together in a shaker.
Rim two glasses with turbinado sugar and fill halfway with ice. Divide the margaritas evenly between the two glasses.
Garnish with peach slices.