Begin by making the ginger syrup. In a blender, combine the water and ginger; then blend until pureed. Transfer this mixture to a small saucepan. Stir in the sugar. Bring the mixture to a boil then reduce the heat to a simmer. Heat for about 10 minutes or until the mixture starts to thicken slightly. Cool completely
For each float, pour about 1/4 cup of the ginger syrup into a glass. Squeeze in two lime wedges and then put the wedges in the glass. Add a pinch of the julienned mint. Then muddle. Fill the glass about 3/4 full with club soda. Add one or two scoops (about 1/4 cup) of lime sherbet. Garnish with a sprig of mint.