You'll need 1 (750-milliliter) bottle of wine. The secrets to this dessert: Make sure all liquids are cold, and don't overfill the freezer container.
Cook first 3 ingredients and 1 cup water in a small saucepan over medium heat, stirring occasionally, 3 minutes or just until sugar dissolves. Fill a large bowl with ice; place saucepan in ice, and let stand, stirring wine mixture occasionally, until cold (about 1 hour).
Pour mixture into freezer container of a 1 1/2-qt. electric ice-cream maker; freeze according to manufacturer's instructions. (Instructions and times will vary.) Spoon sorbet into an airtight container; cover and freeze at least 8 hours.
Combine blackberries and next 5 ingredients; toss gently. Cover and chill up to 2 hours. Serve sorbet topped with berries.
*Riesling or a dry rosé may be substituted.
This was wonderful. I only got to enjoy it twice though before a storm knocked out my fridge for a day and it melted.