Place mint leaves in a medium bowl; set aside. In a medium saucepan combine the water and 1 cup sugar. Bring to boiling, stirring until sugar is dissolved. Remove from heat; pour over mint leaves. Stir in orange juice.
Cover and let stand at room temperature for 1 hour. Strain mixture through a mesh strainer. Stir in bourbon. Cover and chill up to 24 hours.
Place granulated sugar in a shallow dish; wet the edge of 8 glasses and dip into sugar to coat. Add crushed ice to glasses. Divide bourbon mixture among glasses (about 2/3 cup per glass). Garnish with mint and orange slices.