Make Simple Syrup (below).
In food processor, place cherries, orange juice and 1/2 cup Simple Syrup. Cover; process, using quick on-and-off motions, until mixture is pureed. Place strainer over medium bowl; strain mixture through strainer, pressing with back of rubber spatula to extract as much liquid as possible.
Pour juice into 8x8-inch glass baking dish. Cover with plastic wrap. Freeze overnight, or until firm.
When ready to serve, use tines of a fork to shave surface of frozen granita; spoon into bowls. Serve immediately.
In small saucepan, heat water and sugar over medium heat, stirring frequently, until mixture simmers and sugar dissolves, about 3 minutes. Remove from heat; cool.