Potatoes are good nourishing food. Served in their usual manner -- baked, mashed, boiled or fried -- they serve admirably as the background in many a well-balanced meal. But they need not be restricted to the background; they have a potential for playing a more important role on the menu. They can, if given time and attention, show themselves to be a match for any of the more exalted and expensive vegetables.

A gratin dauphinois brought to the table in a shallow au gratin dish, golden and bubbly will be the center of attention, as will thin, crispy potato pancakes, or a high golden potato puff. To accompany them you need only an unsauced roast, steak or chops, and a green vegetable or salad.

CRISP POTATO PANCAKES

(4 servings as side dish) 6 ounces cream cheese 3 tablespoons flour 1 egg plus 1 yolk 1/2 teaspoon salt Freshly ground pepper 1 cup finely diced cheddar or Gruyere cheese 2 pounds potatoes (about 4 cups when grated) 1/4 cup heavy cream

Blend together the cream cheese and flour. Beat in the whole egg and the yolk. Stir in seasoning and diced cheese. Peel and grate the potatoes. A fistful at a time, squeeze out as much of the liquid as you can. You may use a towel for this operation, but your bare hand does as well and is easier to wash. Add the potatoes and cream to the cheese mixture, blending well.

Heat enough butter and oil in a large skillet to generously cover the bottom. When hot, spoon in the batter, shaping them to be about 4 inches in diameter and 1/4 inch thick. Lower heat a bit and cook until they are golden brown on the bottom and holes have appeared on top. Turn and brown the other side. Transfer to an oven-proof platter in one layer and keep warm while cooking the remaining pancakes.

These may be made in advance and put in one layer on a large cookie sheet. Reheat just before serving in a 400-degree oven for about 5 minutes. Do not overheat or they will become dry.

POTATOES GRATIN DAUPHINOIS

(4 servings) 2 pounds boiling potatoes, peeled and sliced 1/8-inch thick 1 large clove garlic, mineced or put through a garlic press 1 teaspoon salt Freshly ground pepper (about 1/4 teaspoon) 1 cup grated Gruyere cheese 1 cup light cream or milk

Put potatoes in a bowl of cold water until crisp. Drain and pat dry. Grease a shallow gratin dish, just large enough to hold the potato slices in two layers. Spread half of them in the dish. Divide over them half of the garlic, salt, pepper and cheese.Arrange the remaining potatoes over this layer and spread the remaining seasoning and cheese over the entire surface. Pour on the cream. Bake for 30 to 40 minutes in a preheated 400-degree oven. Check after 30 minutes. If potatoes seem dry, add a bit of cream. The potatoes must be moist, but no liquid should run on the plate when they are served. They may be prepared in advance, but if so, bake only 30 minutes, then put into a hot oven to finish baking 10 to 15 minutes before serving.

POTATO CHEESE PUFF

(8 servings) 8 medium-size boiling potatoes 1/3 cup butter 1 1/2 cups grated sharp cheddar cheese 3/4 cup milk 1/2 teaspoon salt Freshly ground pepper 1 large onion, minced and sauteed in butter until translucent and tender 2 eggs, well beaten

Peel the potatoes. Boil until well done, drain and mash well. Combine with the butter, cheese, milk, salt, pepper and onion in a saucepan and stir over a low heat until butter and cheese are melted. Fold in the beaten eggs. Turn into a greased, 2-quart casserole or souffle dish and bake at 375 degrees for 45 minutes, until the potatoes are puffy and brown. Bring directly to the table. The dish may be prepared in advance, leaving only the baking to be done just before serving.