1. In a small pot combine the sugar, spiced brandy, water, black peppercorn and cinnamon stick.
2. Bring to a boil, stirring until sugar is dissolved.
3. Cover pot and let set at room temperature for one hour.
4. Strain the syrup through a sieve, whisk in the blackberry puree, vinegar and chill until cold.
5. Transfer to the bowl of an ice-cream machine and freeze according to the manufacturer instruction.