In saucepan, combine vinegar and red wine.
Puree blackberries in food processor or blender. Using fine mesh strainer, strain blackberry puree into saucepan as well. You may need to use a rubber spatula to assist this process. Discard seeds/pulp.
Bring mixture to a boil. Simmer until sauce is very reduced- volume will be about 1 ½ cups. Add sugar and continue boiling until sauce is thick and syrupy.