A copycat of the Filet O fish sandwich found at the golden arches. Introduced by a franchise in Ohio to sell due to the Catholic practice of not eating meat on Fridays. For an authentic "'O-Fish" use 1/2 a slice of American cheese and rehydrated, dehydrated onion. For McDonald's style onions Add 3 parts water to 1 part dried minced onion. Allow Dehydrated Onions to hydrate for about 20 minutes or until fully rehydrated and drain.