This was all the more fun to make as I picked the quart of black raspberries from my back yard. I substituted violet syrup for the creme de cassis (based on what I had in the cupboard--the recipe as is would be good I think). I followed the amounts in the recipe exactly and would decrease the amount of sugar by a quarter or even a half. It's edible as is, though, and if you like sorbet sweet, then it's fine. To get the seeds out of the berry puree was a bit tricky at first. I poured some into the strainer and stirred it vigorously with a spoon to force the juice out.
From EatingWell: July/August 1994
A sorbet is the perfect showcase for this member of the raspberry family; berries ripen from late summer to early fall.