Place the lamb, parsley, garlic, onion, olive oil, paprika, cumin, saffron, salt and ¼ teaspoon pepper in a tagine. Cover with 2 cups water and bring to a boil over high heat. As soon as it comes to a boil, reduce the heat and simmer, covered, until the meat is very tender and the sauce has reduced to a thick gravy, 1 to 1/2 hours. Add water, if necessary, during the cooking time if the sauce gets too thick. Season with salt and pepper, if needed.
When the lamb has cooked 1 ½ hours, place the artichokes and preserved lemons. Cover and cook until the artichokes are tender, 20 minutes. Add the olives and sprinkle the stew with the remaining 1 tablespoon lemon juice. Simmer 2 minutes. Serve the tagine directly from the tagine vessel.