Season the pork chops with salt and pepper. In a very large skillet, heat the olive oil until almost smoking. Cook the pork chops over high heat, turning once, until browned around the edges and just cooked through, about 3 minutes total. Transfer the pork chops to a plate and keep warm.
In the same skillet, melt the butter. Add the leek and cook over moderate heat until tender, about 3 minutes. Add the fennel and apple and cook, stirring occasionally, until softened, about 4 minutes. Add the sage and cook until fragrant, about 30 seconds. Season with salt and pepper, transfer to a platter and keep warm.
Pour the hard cider and any accumulated pork juices into the skillet and boil over high heat until thickened, about 4 minutes. Set the pork on top of the fennel and apples, pour the sauce over the pork and serve at once.