3/4 cup balsamic vinegar.
1 to 2 TBSP brown Sugar optional.
Combine and bring to a boil. Reduce heat to medium low and continue to gently boil for 15 to 20 minutes until it begins to thicken. The volume should reduce to 1/4 to 1/2 the amount. When the back of a spoon is coated then you will know it’s finished. You can also save the leftovers to use at another time!
Make sure that use authentic balsamic vinegar. It should have a foil cover and seal as approved by the European Union. Do not buy the very expensive extra aged.. those are meant for finishing, not to be boiled. I prefer the Modena variety.