Cut the kidneys in walnut-size pieces. Remove the membranes. Saute with the onion in butter or margarine. Remove the kidneys and set aside in a warm place. Add the flour to the pan. Mix with the onions and add the consomme and wine. Simmer 10 minutes, stirring. Return the kidneys to the pan and heat. Serve in a ring of cooked rice, sprinkled with parsley.