Place all ingredients into a blender (or pitcher and blend with stick blender) and blend until smooth. Then pour mixture into a glass pyrex type baking dish with a depth no deeper than a half inch. Separate into two pans if need be, and place on a level spot in the freezer. Now the work begins. Every half hour to forty five minutes take a fork and scrape the partially frozen sides of the mixture to the middle of the baking dish. At this time you want to break up the larger chunks as much as you desire. The more into the freezing step of the process, the larger the chunks will be and the more you will want to break them down. A pastry cutter might assist you in this as it did for me. Unconventional, yes. Effective, very. Ashamed, no. After a couple of hours or so and a few returns to the freezer, your grantia should be sufficiently frozen and slushy. Now you have a choice to make. If you want the granita to be a bit more supple and slushy, serve now. Want it to be a bit more frozen and granular, keep freezing and scrapping, that is, if you have the willpower. Whatever you decide it's going to be worth it. Once you reach the desired consistency, scoop into your chosen stemware, garnish with mint or a quarter slice lemon, serve and enjoy.