Season the chops on both sides with salt and pepper. Heat the oil in a large sauté pan or frying pan over medium heat. Add the bacon lardons and fry until lightly browned, 3 to 5 minutes. Lift them out with a draining spoon and set them aside in a bowl. Add the onions to the pan and sauté over medium heat, shaking the pan often so they color evenly, until browned, 7 to 10 minutes. Remove them with the draining spoon and set aside in a separate bowl. Lastly, add the chops and brown them, allowing 2 to 3 minutes. Turn them and brown the other side, 2 to 3 minutes longer. Take them out, whisk the flour into the pan, and cook until bubbling. Add the wine and bring to a boil, stirring constantly. Stir in the broth and return to a boil. Stir in the lardons, then replace the chops, pushing them down into the sauce, and add the bouquet garni.
Cover the pan and simmer over low heat for 25 minutes. Add the onions and continue simmering until they are soft and the chops are tender when poked with a twopronged fork, 10 to 15 minutes longer. The cooking time will depend on the thickness of the chops. Turn the chops from time to time and add more broth if the sauce gets too thick.
When the chops are tender, transfer them to 4 warmed plates. Discard the bouquet garni, stir the crème fraîche into the sauce, and bring just to a simmer. Stir in the mustard and parsley and take the pan from the heat. The fresh, piquant taste of mustard turns bitter when overcooked, so mustard should not be boiled and should always be added toward the end of cooking. Taste the sauce, adjust the seasoning, and spoon it over the chops. Serve at once.