The Special-when it was first invented by television executives, it was envisioned as an oasis in the vast wasteland. More than just a program that would depart from the routine, it was a distraction, a high spot designed to make you forget all those low spots.

Cooks can make use of the same theory. Every dinner, no matter how ordinary-especially, in fact, if it is ordinary-should have a Special. This is the dish that offers something unique, the dish that is served up with a small story, the dish that can take your mind off the rest of the meal. To put that another way: What does it matter if you've overcooked the chicken, when you've had the wild rice flown in from your farm in Afghanistan? Tonight's Special is the salad dressing.

The Staples: Make sure these are all on hand: salt, pepper, tarragon, dry mustard, cayene pepper, eggs, oil for salad dressing a lemon.

The shopping List: 1 pound ground beef; 1 tin anchovy fillets; 2 large onions; 2 greens peppers; 1 head romaine lettuce; 1 bunch scallious; chivers parsley; 4 ears corn; 1 pound noodles; 2 small cans tomato sauce; 1/2 pound cheddar cheese; 1 small container sour cream; 1 container blueberries.

There are few dinners that are easier and less special than the common casserole. Whether it's macaroni and cheese, noodles and tuna fish or something a little more complicated, like tonight's main dish, it should provide no great test of your growing culinary skills.

Your only test tonight will come with the salad dressing.

Prepare in Advance: The first thing you're going to make is mayonnaise. We all know that it's possible to begin with a jar of the ready-made stuff from the grocery shelf, but then your Special will not be all that special.And if we're going for the classic green goddess dressing-the way it was first made and served in San Francisco's Palace Hotel-we're going to do it the right way, using an electric beater.

We'll need 2 eggs yolks and no egg whites. Separating the yolk from the white requires a steady hand and a certain amount of practice. Break the egg into halves and carefully transfer the yolk from one half to the other allowing the white to fall away.

When you have 2 yolks in a mixing bowl, add a pinch of dry mustard, a pinch of salt and a few shakes of cayenne pepper. Beat this up for a couple of minutes and add just a few drops of salad oil. As you continue beating the egg mixture, add a tiny trickle of oil.

The mixture will thicken and when this happens, you add a total of 2 cups of oil and 3 teaspoons of lemon juice in a slightly heavier but steady stream. Should the mayonnaise suddenly lose its consistency, add an ice cube and beat it into the mixture. Why this works I don't know. But it does. If it doesn't, start over.

To the 2 cups of mayonnaise, you're going to add the anchovy fillets, finely chopped. And 4 scallions-both whites and greens-also finely chopped. And a handful of chopped parsley. A small handful of chopped chives. A large pinch of tarragon.

Store this in the refrigerator until ready to serve.

5 p.m.: And now for the easy part, the casserole. Start 6 quarts of water boiling in your largest pot.

Heat a splash of oil in a large frying pan over medium heat. Add the pound of ground beef, crumbled, and the onions, chopped. A couple of minutes later add the green peppers, cut into narrow strips. Finally, as the meat is browning, slice the kernels of corn from the ears with a sharp knife and add them. A couple of minutes after this, drain away the fat and salt and pepper to taste.

5:30 p.m.: Add the noodles to the boiling water. When cooking pasta, some cooks claim the water should be boiling fiercely. Others say it should be boiling merrily. I'm not sure what the difference is. However, if you put the noodles into the water slowly, you won't interrupt the mood, whether it be fierce or merry.

Cook the noodles a couple of minutes less than the box's recommended minimum time. Preheat oven to 350 degrees.

5:40 p.m.: Drain the noodles and put them into a buttered baking dish. Add the meat-onion-pepper-corn mixture, the 2 cans of tomato sauce and most of the cheddar cheese, grated. Mix this together and scatter the rest of the grated cheese across the top. Bake.

6:20 p.m.: Check casserole to see whether the cheese is properly browned. Rinse the romaine lettuce, pat dry with paper towels and break into small pieces. Add the green goddess salad dressing and explain, as you bring it out, the absolute necessity of using homemade mayonnaise.

The dinner, both ordinary and special, will be followed by blueberries served with a dollop of sour cream. If your dinner should still need a special touch-Special touch, that is-try adding a shot of maple syrup and a dash of cinnamon to the berries.