Wild black raspberries grew up the entire length of the driveway, intertwined into a stone wall my grandfather had laid on our farm, all the way to our pig barn. We picked them often during the summer and froze them. I love growing some of our own berries to use in desserts, jams and specialty drinks like this one.
In a medium saucepan over low to medium heat, soften the blackberries and raspberries with about 1/2 cup of water. Cook them until they are very soft. Use a hand food mill or a fine mesh strainer to separate the juices and seeds. Let the fruit juice cool, and discard the seeds and skins. In a medium saucepan, dissolve the sugar in the water, making a simple syrup.