Using cookie cutter cut out mozzarella hearts. Using a serrated knife cut equal size tomato slices.
Pour vinegar into a small pot. Turn kitchen fan on to help with the strong vinegar fumes.
Bring to a simmer over medium-high heat then turn down heat to keep at a low simmer.
It will take about 10-15 minutes to thicken and reduce. The vinegar should be able to stick and coat the back of a spoon to know that it is ready. On a platter make a pattern alternating tomato slices, basil leaf and fresh mozzarella. Drizzle balsamic reduction, and olive oil and season with salt and freshly ground pepper.