Take Fried Fish Jewish Style, a popular recipe in 19th-century England. Most non-Jews, when they made their fish and chips, cooked them in lard or beef drippings in the period before Spry, Crisco and other vegetable shortenings.
Jews, however, could not use lard, made from the prohibited pork, so they fried their fish in olive oil, after it was first salted and dipped in flour and water.