Sorbets and Granitas
Sorbets
and granitas are basically sweetened, frozen water. Sorbets are frozen
while being churned. This makes for very fine ice crystals, and
sorbets are generally very smooth and almost creamy in the mouth. A
granita is frozen still and scraped every so often with a fork. This
encourages large ice crystals to form and leaves you with a very icy,
granular end product which can be very refreshing.
The sugar in
your sorbet/granita solution helps to regulate the size of the ice
crystals and also how firmly it freezes. Too little sugar, and you've
got a frozen brick. Too much, and it won't freeze at all.
Here
is a neat little trick for testing your liquid for sorbets. Wash a
fresh egg very well. Dry it. Float it in your liquid. Some of the
egg should float above the liquid. You want this area to be about the
size of a dime to a nickel. If too much is sticking out, add some
water to dilute the solution. If too little is sticking out, you need
more sugar. Add some simple syrup or some corn syrup. Once your
liquid has passed the egg test, it's ready to chill, then either be
churned into sorbet or frozen and scraped into granita. And there you
have it.

Here's some pomegranate sorbet. And here's some pomegranate granita.
Here's a very basic outline of how to make sorbet/granita:
Flavorful juice/fruit puree/wine, etc
1:1 simple syrup (steep whatever you want in it)
a little corn syrup or a wee splash of alcohol (this helps to further inhibit serious crystallization)
salt to taste
water
lemon juice or lime juice (to balance sweetness)
Heat
your juice to dissolve the salt. Add some simple syrup and some
lemon/lime juice. Taste to see if you like it. It should be a little
sweeter than you want it, because freezing will dull some of the
sweetness. Float your clean egg in it. Add some water or some
more simple syrup until your sugar density lets the egg float with a
dime-nickel size above the liquid. Add a splash of alcohol. Put in a
shallow pan in the freezer for granita or chill then spin in your ice
cream maker for sorbet.
Homemade sorbet should be eaten fairly
quickly since it isn't stabilized with commercial stabilizers and it
will start to separate.