Heat the oil in a casserole dish over medium-high heat. Season the goat shoulder with salt and pepper and place into the dish. Brown quickly on all sides. Add the onions to the pan and cook, stirring constantly until browned. Mix in the prunes and preserved lemon; cook and stir for a few minutes to blend the flavors. Pour in the red wine and chicken stock and bring to a simmer.
Cover the casserole dish and bake for 2 hours, or until meat is so tender that it falls off of the bone.