Balsamic vinegar
This is what was specified by the recipes we made when we used this ingredient.
In Recipes Calling for:
Balsamic vinegar
What a strange ingredient for a cocktail, right? The idea becomes a lot less strange when you consider that we add acidic flavors to cocktails all the time in the form of citrus juice. Balsamic fills the same role of balancing sweetness while adding its rich flavor to the mix. It especially works with robustly flavored dark spirits like whiskey.

