CARAMELIZED ONIONS

~ Susan Williams/That Susan Williams

2 T. olive oil
2 T. unsalted butter
2 lb. onions, peeled and sliced in half-rounds
1/2 t. fresh thyme leaves
2 T. balsamic or sherry wine vinegar
1 t. kosher salt
1/2 t. pepper

Heat olive oil and butter in large pan.  Add onions and thyme, tossing with the oil.  Place lid on pan and cook over medium-low heat for about 10 minutes to sweat the onions.  Remove the lid and continue cook for 25-30 minutes, stirring occasionally, until the onions are caramelized and golden brown.  Add the vinegar, salt, and pepper and cook for two more minutes, scraping the brown bits from the pan.  Season to taste.