Combine sugar and water in small saucepan. Bring to a boil, remove from heat, and allow to cool.
Place all ingredients, including sugar water, into blender, and process until smooth. (Depending on blender capacity, you may need to do this in batches.) Pour mixture into a 9x13 metal pan, and place in the freezer. Every 30 minutes or so, scrape and stir with a fork.
After about 2 hours, Granita should be close to frozen. Give it a last scrape and stir, then divide among chilled bowls, and garnish with mint sprigs.