Combine the sugar and water over low heat until the sugar has dissolved. Add the mint. Remove the pan from the heat and let cool.
Puree the fruit in a food processor until liquefied. Pour the fruit into a medium bowl and add the salt. Remove the mint leaves from the syrup. Add the syrup to the pureed fruit and mix well.
Pour the cantaloupe mixture into a pre-chilled 7 by 12-inch glass baking dish. Place it uncovered into the freezer. Stir with a fork every 1/2 hour until almost completely frozen but still grainy, about 3 to 4 hours.
Cooking Notes: This works best in 2 glass loaf pans or one 7 by 12-inch glass baking dish. The only critical point here is NOT to stir it past the almost frozen state or the ice crystals will become too fine and hard to scrape.
Entertaining Notes: To serve, find a really interesting glass or bowl and dip it in cold water. Put the bowl into the freezer for 15 minutes; repeat. The result will be a frosted glass that looks great and sets the right backdrop for the granita.