Blackberries are one of the great culinary joys of late summer. They ripen at a time when most other berries are finishing, and though they tend to be a little sour when eaten fresh, they have fantastic flavor as well as a rich dark purple color when cooked. They are also great in that they are relatively easy to pick, since the berries are large and sturdy, with a central core that makes them far less fragile than raspberries.