Preparation Put oven rack in middle position and preheat oven to 350°F. Pat chops dry. Heat oil in a 12-inch heavy skillet over moderately high heat until hot but not smoking, then brown chops in 2 batches on one side only, 3 to 4 minutes per batch. Transfer chops, browned sides up, to a large shallow baking pan, reserving skillet. Bake chops until heated through, about 20 minutes. While chops bake, melt butter in skillet over moderate heat until foam subsides, then cook onion with sugar and salt, scraping up brown bits and stirring occasionally with a wooden spoon, until onion is softened, 8 to 10 minutes. Add cider and vinegar and boil mixture, stirring occasionally, until onions are tender and liquid is reduced to a glaze, about 10 minutes more. Serve chops with glaze.
Preparation Put oven rack in middle position and preheat oven to 350°F. Pat chops dry. Heat oil in a 12-inch heavy skillet over moderately high heat until hot but not smoking, then brown chops in 2 batches on one side only, 3 to 4 minutes per batch. Transfer chops, browned sides up, to a large shallow baking pan, reserving skillet. Bake chops until heated through, about 20 minutes. While chops bake, melt butter in skillet over moderate heat until foam subsides, then cook onion with sugar and salt, scraping up brown bits and stirring occasionally with a wooden spoon, until onion is softened, 8 to 10 minutes. Add cider and vinegar and boil mixture, stirring occasionally, until onions are tender and liquid is reduced to a glaze, about 10 minutes more. Serve chops with glaze.