Quick, easy and flavorful are the key words to summer sides! I was grilling a pork tenderloin one night and wanted something to go with it that was as little work as possible with the most flavor, this is it for sure!!!! —Danielle
In a small sauce pan heat the balsamic vinegar to a low boil and reduce until its very thick and about 1/2 cup is remaining. This will take about 15-30 minutes. Be very careful not to burn it. Let it cool completely. This can be made up to a week ahead.
Split the peaches in half and remove the stone. Peel and slice the onion in 1/2" slabs. Drizzle both with olive oil and salt and pepper. Grill the peaches and onions for about 7 minutes or until they have nice dark grill marks and the juices have started to really run. The onions can be grilled longer if you like them well done. Remove from grill and give them a rough chop, keeping the pieces on the large side. Toss with the cubes of mozzarella.
On a large platter pile up the grilled peaches, onions and mozzarella. Drizzle the balsamic glaze over the top. Enjoy!