In a saucepan on medium heat, bring the vinegar to a boil. Reduce the heat and simmer for 20-25 minutes until the sauce has reduced by half and is thick like syrup.
Take off heat and let cool for 10 minutes.
Store in a sealed jar.
I use this for savory dishes. Some recipes add sugar, honey, or maple syrup. I consider this a balsamic syrup that I would use in desserts, or when I want a sweet note in a dish.But for my savoury dishes, I use this recipe. It's sometimes called a balsamic reduction.