1. Place sugar and 3/4 cup water in a medium saucepan over high heat; cook 1 minute or until sugar dissolves, stirring constantly. Stir in juice and rind; remove from heat. Pour juice mixture into a 13 x 9–inch baking pan. Cool to room temperature. Cover and freeze at least 8 hours or until firm.
2. Remove mixture from freezer; scrape entire mixture with a fork until fluffy.