Heat half of the butter in a large sauté pan over medium-high and place the chops in the pan. Brown the chops, 2 or 3 at a time, and set the chops aside as they are finished.
Turn the heat in the pan down to medium and add the other half of the oil or butter. Sauté the onions until soft, scraping any fond from the bottom of the pan into the mixture. Add the apple slices and cook for about 4 minutes or until they are just beginning to become tender, then add the maple syrup and vinegar and cook down for about 2 more minutes.
Season with pepper and serve the apples and sauce over the warm, browned chops.