This recipe makes a smooth, deep purple sorbet sexed up a bit by the addition of a little liqueur. I make this sorbet with wild mulberries from a tree near my house, but blackberries would be just as good, as would black raspberries. As for the liqueur, try to find cassis, which is made from blackberries. Most liquor stores carry it. I happen to have homemade elderberry liqueur around in the house, however, so I used that instead. You also could use Port wine.