Place potatoes in cold water to cover over high heat. Bring to a boil and cook for about 15 minutes or until potatoes are almost cooked through. Drain. Heat oil in a large, heavy-bottomed casserole over medium heat. Add the celery and sauté for about 5 minutes, then add onion and sauté until vegetables begin to get soft. Add the olives and sauté for an additional minute. Stir in the tomatoes and their juice. Bring to a boil. Lower heat and simmer for 10 minutes. Stir in broth and return to simmer. Stir in the potatoes and the soaked baccala and simmer for about 10 minutes or until the potatoes are cooked and the baccala flakes when poked with a fork. Taste and, if necessary, add salt. Serve hot. Note: Often salt cod dishes will require no additional salt. Therefore, always taste before adding any seasoning.