From a third cousin, twice removed, who worked at a Luby's in the 80's, he said the non copyright-able list of ingredients was something like this:
A cup of cooked bacon pieces
2 cups of shredded American cheese (8 oz)
1/2 cup of sliced green onions
8 slices of white bread without the crust
1/2 of beef broth
1 tablespoon of kosher salt
2 teaspoons of ground pepper
3 lbs of ground beef chuck
2 XL eggs
mix the bacon, cheese, and onions and set them aside, break bread up by hand and mix it with the broth in a bowl to get it soft, add the salt, pepper, chuck and the eggs, and get it mixed well. Divide it up into 8 portions, make them into a ball then flatten them to an oval shape, keep them in the fridge until you are ready to cook. In a large skillet about medium heat cook the ovals a few minutes each side (about 3 min per), when cooked place in foiled lined baking sheet, top with the bacon, cheese, onion mixture. and place in a preheated 350 F oven for a few minutes to get the cheese melted, these are then topped with a "natural gravy", which is essentially an au jus, found with the powdered gravy, chili mixes and other powdered things at your local super market
The natural gravy had beef broth, pan drippings, worcestershire sauce, kitchen bouquet seasoning, black pepper, bay leaves and salt to taste.
I considered it blasphemy to consume a Luby's cheese steak without a side of mac n cheese, again my distant cousin, said the ingredients included:
8 oz macaroni
4 tablespoons nonfat dry milk
2 tablespoons flour
1 tablespoon butter, melted
1 1/4 boiling water
12 ounces shredded American cheese 1/4 teaspoon salt
cook the pasta per package directions, drain it, in bowl mix the milk, flour, butter, whisk and add water slowly, add a cup of cheese and keep on whisking until smooth and creamy, add in the macaroni and another cup cheese and the salt, transfer to a casserole dish, cover with foil and bake for 30 min, remove the foil and add remaining cheese on top, while you are at it, go get some more cheese and get the pasta nice and covered, because you really can't have too much cheese, right? Put it back in the oven, uncovered until the cheese on top melts, dig in!!!