Preparation Pulse berries with sugar (if using) in a food processor until finely chopped and very juicy. Transfer to a bowl and add vinegar. Let stand 1 hour. Strain vinegar thourough a fine-mesh sieve into a bowl, discarding solids. Cooks' note:Vinegar keeps, covered and chilled, 1 week.
Preparation Pulse berries with sugar (if using) in a food processor until finely chopped and very juicy. Transfer to a bowl and add vinegar. Let stand 1 hour. Strain vinegar thourough a fine-mesh sieve into a bowl, discarding solids. Cooks' note:Vinegar keeps, covered and chilled, 1 week.