This is my version of the venerable Maraschino cherry except with blueberries. I often refer to this garnish as Boozy Blueberries on the site.
We are using dried blueberries in this recipe. Fresh blueberries contain a lot of water so getting alcohol to infuse into them presents a problem. With other foods such as pickles, salt is used to extract water from the food before infusion with a flavored liquid such as a brine. We don't want to make pickled blueberries here so starting with dried berries is the way to go. I find mine at Whole Foods (expensive) and Trader Joe's (cheaper).
Add booze and bitters to a jar. Add dried blueberries so that they take up about 2/3 of the volume of the liquid. You want 1/3 of the liquid to be on top of the berries to allow for expansion as the blueberries absorb the booze. Seal the jar and leave it at room temperature 3 days or up to a week. Then store in the fridge. They will keep for many months (I have gone 8 months with no problems).
Unlike dried cherries, the blueberries remain inky dark blue and don't leach any color. You can use these delightful little bundles of flavor as you would Maraschino cherries. They go especially well in Tequila and rum based cocktails such as a Tequila Old Fashioned with grapefruit bitters.
The blueberries never quite expand to their pre-dried size so they have a nice slightly chewy texture. There is a nice vanilla-ish flavor from the Licor 43 with the bitters balancing out the sweetness from the liqueur.
I would like to experiment with some aged rum and maybe tweaking the liqueur. If anyone wants to beat me to it let us know how it turns out.