ALTHOUGH brunches are said to be a distinctly American form of entertaining, food historians don't give any credence to the idea. The combination breakfast-lunch meal probably started in the 16th century in Vienna, where people enjoyed a midmorning meal called Gabelfruhstuck, meaning ''fork breakfast.''
At that time, and perhaps even now for some Viennese, the custom was to have five official meals a day. Early breakfast was mostly liquid - hot chocolate or other beverages - but at midmorning there was food that required a fork.
The custom of having fork food in the middle of the morning spread throughout Europe, among the wealthy classes, of course. One food dictionary explains that brunch started in upper-class British society and came to the United States from there, which sounds logical enough.
Whatever its specific origin, brunch is always a combination of breakfast and lunch foods. It is an event that increases and wanes in popularity, never really going out of style and always open to new interpretations.
Today many people like extremely informal brunches at home, with everyone in the kitchen making his own popovers, Huevos Rancheros, scrambled eggs, or waffles. Brunch can also be a formal sit-down affair, but most are very casual, sometimes festive, occasions.
Menu ideas for brunch are limitless. Some of the best come from The Bakery restaurant in Chicago, where every brunch is different. Chef Louis Szathmary says he often offers three menus at the same brunch.
One menu is very French with a veal dish, a puffy omelet in cheese or a mushroom omelet, traditional French breakfast pastries such as brioches and croissants, and a fruit compote.
The second menu might have Hangman's Fry - scrambled eggs with tiny Olympia oysters. The Bakery's third menu is a complete Hungarian brunch.
Interesting, unusual foods are often served at this meal around the world. At brunch in Bombay in a private home I was once served several egg dishes spiced with cumin and coriander. One in particular was called Camel's Humph Kabob.
In Venezuela I have had excellent hash of roast beef and chili peppers.
A delicate, fruity red soup was served to me around midmorning one gray day in Norway, and in Denmark I tried a raw egg with herring, which is traditional and very popular.
When it comes to creamy hot oatmeal or oatcakes at early breakfast or brunch, there's nothing like the oats in Scotland and the wonderful ways they've been preparing them for years. Their jams and marmalades are also some of the best in the world.
One must credit many large hotels with lavish buffet brunch tables, for they often serve a tremendous variety of food in a most attractive, decorative manner , at a most attractive price.
Not the least of the attractions, of course, is the freedom to serve yourself and to have more than one helping of dishes you like best.
The Arizona-Biltmore Hotel in Phoenix, Ariz., offers a splendid brunch with 20 or more kinds of fresh fruit. In New York City, the chicken hash at ''21'' is legendary.
In New Orleans the jazz brunches with Cajun and creole dishes are a must for any visitor.
Last year at the Drake Hotel in Chicago I went to a delightful brunch where various kinds of soup were served, one Oriental, another made with citrus fruits , the third for a vegetarian diet.
Another time at the Drake there was a choice of six cereals with many kinds of toppings, including yogurt, honey, heavy cream, skim milk, dried and fresh fruits, colored sugars, and chopped nuts.
Buffet is a word that automatically goes with the word brunch for some people , but Richard Perry in St. Louis says he doesn't like to keep hopping up and down at brunch or at salad bars. At his restaurant he gives his customers brunch , but with table service.
''My favorite meal has always been the Sunday brunch,'' he says, ''because we serve a kind of 'down home' food with lots of the things I remember as a kid.
''You may not believe it, but our most popular food at brunch is oatmeal. We serve it hot with raisins, brown sugar, and heavy cream, and everyone likes it.
''Here at the Richard Perry Restaurant we think of brunch as a three-course meal with fresh fruit, then cereal or crepes, and a third course of egg dishes and breakfast meat such as our Missouri country ham or the very fine Italian prosciutto made locally.
''Another favorite at the Richard Perry Restaurant is smoked pork chops with a sweet and sour peach sauce. And another especially nice one we call a muffin, but it's really a timbale made of chicken breast and prosciutto, rolled and sliced, with a mousse of veal sweetbreads and romaine lettuce, served with an orange Bearnaise sauce.
''We also serve Eggs Benedict and wonderful chicken hash with poached eggs. This week we had a compote of fresh strawberries and the first rhubarb of the season.''
Some American brunches take a cue from the traditional large English breakfasts. One of the best ones I've ever had was called a Victorian brunch by Chef John Tovey, owner of Miller Howe, a country inn in England's Lake District.
Porridge and kidneys are two of the regulars on Tovey's Victorian brunch menu. The porridge comes with demerara sugar and butter. Then there's Creamed Smoked Haddock in Puff Pastry, Deviled Kidneys, and what Chef Tovey calls a Hearty Lakeland Platter of bacon, egg, sausage, tomato, fried bread, apple, mushroom, and potato.
But when it comes to strictly American dishes, few are more popular than the combination of English muffins, smoked meat, poached fresh eggs, and Hollandaise sauce known as Eggs Benedict.
This elaborate sandwich is the all-time favorite food for brunch, and it never seems to go out of style.
It all started in old New York City when a Wall Street stockbroker named Lemuel Benedict ordered toast, a few slices of crisp bacon, two poached eggs, and Hollandaise sauce.
Later, Oscar of the Waldorf admired the idea and copied it, but some say he became a Benedict Arnold by changing some of the ingredients.
The famous New York chef used English muffins instead of toast and ham for bacon. He also added truffles and glace de viande, a meat extract.
Today either Canadian bacon or ham is used, and more often than not both the truffles and glace de viande are forgotton.
At the Ritz-Carlton Hotel in Boston, where an elegant brunch is served every Sunday, there are real truffles on the Eggs Benedict, and Executive Chef John Vyhnanek assures me it's one of the most popular dishes.
A Veal and Chanterelle Crepe is probably the most popular new dish, the chef says. It's on the hot-buffet table with the Eggs Benedict, Eggs a la Ritz, Finnan Haddie in Cream, Roast Lamb, Roast Rib of Prime Beef, Roast Turkey, and Roast Beef Hash in Fried Potato Skins.
There's also a buffet of cold dishes at this hotel and another with pastries and puddings, fruit tarts, and old-fashioned custards.
Here is a recipe for Roast Beef Hash, a familiar menu item with a new twist. It is served in hollowed-out, red-skinned potatoes that have been deep fried. Ritz Roast Beef Hash 3 cups chopped cooked roast beef 3 medium potatoes, cooked, peeled, chopped 1 onion, minced 1 cup brown sauce, or less, to bind Salt to taste Freshly ground black pepper 4 tablespoons butter
Combine ingredients except butter and mix. Heat butter in a saute pan, add hash, and cook over medium to high heat, stirring often, until brown underneath.
Turn over with spatula and brown other side. Cook about 20 minutes in all. Serves 4.
Serve with tomato ketchup and pickles.
If desired, serve in medium-size red-potato skins that have been deep fried. Bake round, well-shaped potatoes. Scoop out center and use for another dish. Deep-fry the skin, retaining the round shape. Stuff with hash. Pasta Primavera a la Ritz 1 pound pasta, preferably rotini 1 tablespoon olive oil 1 large red bell pepper, cut in julienne, about 1/8 by 2 inches 6 shallots, minced 1 clove garlic, minced 3 tablespoons sweet butter 1/2 pound fresh green asparagus, 1-inch pieces, cooked al dente 1/2 pound broccoli in small pieces, cooked al dente 1/4 pound green beans, cut in 1-inch pieces, cooked al dente 24 black, pitted olives 2 tablespoons fresh basil 1/4 cup parsley, chopped 2 teaspoons fresh ground black pepper 3 cups heavy cream 1 cup grated Parmesan cheese 1 tablespoon salt
Cook pasta in boiling, salted water with olive oil until al dente, about 10 minutes. Drain and cool. Saute red peppers, shallots, and garlic in sweet butter over medium heat for 2 minutes in a large pot, 8 quarts or larger. Add all ingredients except salt. Cook 5 minutes or until hot over medium heat. Add salt to your taste. Serve in a heated serving bowl. Serves 8.