Melt the butter in a medium pan.
Cut the onion in half. Thinly slice each half. Add to the melted butter.
Sauté until Onions are tender and translucent, about 5-6 minutes.
Once Onions are translucent, sprinkle with the Brown Sugar. Stir to coat the Onions. Cook, stirring frequently, until light brown and caramelized, about 5 more minutes.
Add the quartered Cherries. Stir and cook for about 5 minutes until the moisture from the Cherries evaporates.
Add the Cherry Juice and Balsamic Vinegar. Stir and reduce for about 5 minutes, until thickened.
Remove from heat and set aside.