Blueberry Shrub

Directions

1. 1
   Place the blueberries in a nonmetallic container. Add the vinegar. Cover tightly and refrigerate for at least 3 days.
2. 2
   Pour the vinegar-marinated blueberries into a sieve over a bowl; press the berries to release all their juice. Discard the solids.
3. 3
   Pour the blueberry liquid into a medium saucepan. Add the sugar and boil for 3 minutes, stirring occasionally. Remove from the heat and let cool. Pour the sweetened blueberry liquid into a small container and chill.
4. 4
   To make each drink, add 1/4 cup blueberry concentrate to a medium cocktail glass filled with ice and add 1 cup cold water. Garnish, if desired.