3 red onions, sliced
¼ cup balsamic vinegar
¼ cup extra virgin olive oil

1 teaspoon kosher salt
½ teaspoon pepper

Preheat into 375ºF
. Cut the onions in half and slice ¼-inch think, place on a baking sheet and toss with balsamic vinegar, olive oil, salt and pepper. Bake for 20 minutes, until the onions are tender.