In a medium saucepan over medium-high heat, combine water, sugar and 1 cup mint leaves. Cook, stirring frequently, until sugar is completely dissolved, 10 minutes; strain and let cool completely.

In a medium bowl, combine syrup and remaining ingredients. Place mixture in ice cream freezer, and freeze according to manufacturer’s instructions, until firm; store in freezer.

To serve, spoon sorbet into bowl or glass, and garnish with mint sprigs, if desired.