In a small pot, heat sugar and 2/3 cup water until sugar is dissolved. Stir, if necessary, to help sugar melt.

Cool. Pour liquid into blender cup, or into food processor fitted with the knife attachment. Add rest of ingredients and blend until slushy. Pour into a large container and freeze overnight.

Cut frozen mixture into chunks and process in small amounts until entire mixture is blended again. (This gives it the sorbet texture.) Freeze until serving.

Remove from freezer a few minutes before serving just to soften slightly. Serve small scoops in lemon halves, if desired. Top with a mint leaf.