Combine the water and sugar in a clean saucepan over medium heat. Stir until the sugar is completely dissolved. (The water doesn't have to come all the way to a boil, but it's okay if it does.) Allow this simple syrup to cool.
Add the other ingredients and stir completely. Pour into a nine-by-thirteen-inch metal pan, and put into the freezer. After 20-30 minutes, stir the mixture with a fork. Repeat that every 20 minutes or so, increasing the frequency a little when the mixture becomes a slush. When the stirring results in dry crystals, you're finished. Cover the pan with plastic wrap and hold in the freezer until serving time
