Combine the sugar, salt and water in a small saucepan and bring to a boil. Remove from the heat and stir in the juices and the vodka.
Strain into a bowl, cover and chill in the refrigerator until cold.
Freeze the mixture in an ice cream maker according to the directions that came with your model.
Transfer the sorbet to a lidded shallow freezer container (plastic or metal are best). Cover the sorbet with a piece of plastic wrap, then cover and freeze 2 or 3 hours before serving.
Notes
The sorbet is best enjoyed up to 3 days after churning.
Before starting, chill both the sorbet mixture (and the pan if not using an ice cream maker) to speed freezing.
Alcohol is optional, but it helps soften the texture and smooth any icy grains while the sorbet freezes. Keep in mind that the sorbet will melt faster when you serve it, though.
To make sorbet without and ice cream maker:Choose a shallow (less than 1-inch deep) metal pan and freeze it for at least an hour before making the recipe.
Follow the recipe to make the fruit syrup base.
Pour the chilled base into the pan, cover tightly with plastic wrap and freeze.
Scrape the mixture with a fork, moving the sorbet from the edge to the center, every 30 minutes or so to break down the ice crystals.