Savor this refreshing frozen dessert in the height of summer when fresh blackberries are at their best.
Thaw berries, if frozen. Meanwhile, in medium saucepan combine sugar and gelatin; stir in milk and water. Heat just until gelatin dissolves. Set aside to cool.
In a food processor bowl process berries until smooth. Press through sieve; discard seeds. Stir berry puree, yogurt, orange peel, and orange juice into gelatin mixture.
Turn into a 2-quart electric ice-cream freezer. Freeze according to manufacturer's directions. (Or, pour into a 9x5x3-inch pan. Cover; freeze about 6 hours. Break into chunks. Transfer to a chilled bowl. Beat with an electric mixer until smooth but not melted. Return to cold loaf pan. Cover; freeze about 8 hours.) Makes six 1/2-cup servings.
Store in airtight freezer container up to 2 weeks.