Pour the aged balsamic vinegar into a small saucepan over medium heat. Add honey or maple syrup if using.

Bring to a gentle boil, then reduce the heat to low and let it simmer for 10–15 minutes, stirring occasionally.

It’s ready when the mixture has reduced by about half and coats the back of a spoon. Don’t over-reduce—it will continue to thicken as it cools.

Use immediately or cool to room temperature and transfer to an airtight container. Refrigerate for up to 1 month.