Muddle blueberries with sugar in a quart (or other large container)
Coarsely chop basil and add to blueberry sugar mix.
Stir in vinegars until sugar is distributed (it won’t completely dissolve).
Cover and set in fridge for five days. Stir or otherwise agitate daily.
At the end of 5 days strain into another container using a fine mesh strainer or a couple layers of cheese cloth. Press or squeeze to extract all liquid from the blueberries. Store in the fridge for up to one month.