Frozen Rhubarb Daiquiris

Combine rhubarb and water and bring to a boil over medium heat. Stir in sugar and heat until sugar is dissolved and rhubarb is soft. Remove from heat and strain. Let the liquid come to room temperature. Combine remaining ingredients, add rhubarb juice, and freeze. Stir occasionally while mixture freezes. To serve, simple spoon frozen daiquiris into glasses and top with a sprig of mint.