- Whisk together buttermilk, honey, 3 tablespoons of sugar, the vanilla, and orange zest in medium bowl until sugar is dissolved. Pour buttermilk mixture into ice-cream maker and freeze according to manufacturer’s instructions. Transfer sorbet to freezer container and freeze until firm, at least 4 hours or up to 2 days.
- To make sauce, combine 1½ cups of blackberries and remaining 1 tablespoon sugar in small bowl. With fork, crush berries until very coarse puree is formed; let stand 10 minutes. Stir in remaining ½ cup blackberries and chopped mint. (Can be made up to 4 hours ahead and refrigerated.)
- To serve, scoop sorbet into 6 dessert dishes and top with ¼ cup blackberry sauce. Garnish with mint sprigs.
- Per serving: about 2/3 cup sorbet with 1/4 cup blackberry sauce
If you don’t have an ice-cream maker, you can freeze the buttermilk mixture in a shallow baking pan until solid, about 4 hours. Let stand at room temperature to slightly soften, then break it into chunks and pulse in food processor until smooth.