1.) Place the vinegar in a small saucepan and heat to boiling. (You might want to open your kitchen windows. This gives off strong fumes!)
2.) Turn the heat way down and simmer uncovered for 30 or so minutes, or until the vinegar is reduced in volume by about half. Transfer to a bowl, cover tightly and store indefinitely at room temperature.
Note If it becomes too thick as it sits around, you can loosen it up by zapping it briefly in a microwave.
Author Recipe from Mollie Katzen’s Vegetable Heaven