Combine first 3 ingredients in a medium saucepan. Cook, stirring constantly, over medium heat 3 minutes or just until sugar dissolves. Place pan in a large ice-filled bowl; cool completely, stirring occasionally.
Stir in orange rind and juice. Pour mixture into a 13 x 9-inch glass or ceramic baking dish. Freeze until partially frozen (about 2 hours). Scrape with a fork, crushing any lumps. Freeze, scraping with a fork every hour, 2 hours or until completely frozen. Spoon into dessert dishes.