The Filet-o-Fish is, if not the most inspired menu item available at McDonald's, then certainly the most divinely inspired. The sandwich was invented in 1962 by McDonald's franchise owner Lou Groen, whose store was located in a predominantly Catholic neighborhood of Cincinnati. Many of Groen's patrons followed the practice of abstaining from meat as a matter of religious observance, and so spent many of their Fridays (during Lent and, for some, during the rest of the year) not eating the burgers he served up. This was bad for business.
Groen rectified his problem the way hundreds of years' worth of Catholics had: by replacing red meat with fish. He created a "burger" consisting of a fried fish filet patty, a steamed bun, a squirt of tartar sauce, and processed American cheese -- giving rise, five layers later, to the glorious, golden-hued creation that lives on in our hearts, minds, and stomachs as the Filet-o-Fish.
The sandwich was the first non-hamburger menu item brought in by new McDonald's company owner Ray Kroc, after it handily bested Kroc's own meatless creation (the "Hula Burger," featuring grilled pineapple with cheese on a cold bun) in a sales competition. The Filet-o-Fish was added as a McDonald's offering starting in 1963 and adopted on menus nationwide by 1965. And it has remained there, relatively unchanged, since then.
But you don't need to go to McDonald's to experience one of these fishy-and-fresh-vegetable-free concoctions for yourself. Thanks to the fantastic "McMenu: Do-It-Yourself McDonald's Restaurant Recipes," you can make your own version at home -- a version that is nearly as disgusting, and nearly as wondrous, as the original.
To get Mickey-D-like results, though, you'll need to put particular thought into not just the ingredients you choose for your creation, but also the equipment you use to create it. McDonald's, you see, achieves its distinctive McDonald's-iness through a process it calls "Q-ing" -- essentially, "helping the flavors to meld via mechanical means." (The Q, apparently, stands for "quality.") The procedure usually involves microwaving, though it can also mean steaming and toasting and otherwise making use of machinery to impart moisture and/or remove it from the foodstuffs in question.
You yourself can achieve a faithful replica of the fish sandwich's particular Q-ing process via a combination of a warm oven, a microwave, and several strips of wax paper. Here's the recipe (from page 18 of this lengthy document):
Filet-o-Fish Tartar Sauce
1/2 cup Kraft Miracle Whip
1/4 cup Vlasic dill relish
2 teaspoons dried, minced onion
2 teaspoons half & half
1 teaspoon dried parsley flakes
1/2 teaspoon lemon juice concentrate
10-12 capers (small), minced
1/8 teaspoon sugar
Combine in a small jar, mix very well, and refrigerate in an air-tight container until needed. Make this tartar sauce well in advance. (The flavors need to "meld.")
1 Van de Camps frozen breaded whitefish patty (Use any square whitefish patty -- not extra crisp -- like Mrs. Paul's, or even the store brand.)
1 small, regular hamburger bun
1 tablespoon prepared tartar sauce
1/2 slice real American cheese
1 dash salt
1 12"x12" sheet of waxed paper (to wrap)
Pre-heat your oven to warm. (This is your warming "bin.")
Cooking Your Filet-o-Fish
Pre-heat your fryer to 375-400 degrees. After it's ready, cook the fish 3-5 minutes until done. (Do NOT thaw first.)
Remove and add a dash of salt.
In the old days, the bun was quick warmed using a steamer. We'll use the microwave. Microwave the bun for about 10 seconds, until hot and steamy. (Do NOT toast the bun) Add about 1 tablespoon of prepared tartar sauce to crown side of the bun. Place the cooked fish filet on top, add 1/2 slice American cheese centered on the fish, and add heel of the bun. Wrap in a 12"x12" sheet of waxed paper and warm in oven's lowest setting for 8-10 minutes. Dig into a fabulous Filet-o-Fish!
An alternate "Q-ing" method would be to wrap the sandwich tightly in wax paper, let sit for 5 minutes, and microwave on high for 15 seconds (while still wrapped).
So there you have it. If you'd like more along these lines, there are many additional McDonald's hacks (including a MacGyvered Big Mac, a healthier version of sweet-and-sour dipping sauce, and a french fry recipe that calls for sugar, corn syrup, shortening, and beef lard) here.