Balsamic glaze is just balsamic vinegar that has been reduced. When the balsamic vinegar reduces, it takes out some of the vinegar flavors and becomes sweeter and thicker in consistency. To make a balsamic glaze, simmer in a pot on the stove over medium heat for 10-15 minutes or until thickened. Be careful not to fully boil or over-reduce it as it will become gummy in texture. The ideal consistency is that of honey or thickened syrup.