For the mixed berries, you can use any combination of berries in addition to the strawberries (we prefer to use at least two), and you can substitute frozen for fresh.
Instructions
Toss blueberries and strawberries with sugar in bowl. Cover and refrigerate for 24 hours, stirring occasionally.
Strain berry mixture through fine-mesh strainer into medium bowl, pressing on solids to extract as much liquid as possible; discard solids. Whisk in vinegar.
Shrub syrup can be stored in an airtight container for up to 1 month. Shake well before using.