THIS IS a Sunday lunch to provide the inner fuel needed for an icy winter day. The centerpiece is a cassoulet, an addictive concoction of beans and various meats cooked to an unbelievable richness and fullness of flavor. The cassoulet is served in solo splendor, with guests starting cautiously with small portions. Inevitably seduced by the dish, they then go back for more, and sometimes even more. Which is why it is charitable to serve cassoulet at lunch, rather than dinner, when its inclination to lie heavily throughout the night can become all too real. Should the cassoulet be served in the evening, it could be preceded by marinated red peppers with anchovies--an obliging first course with enough assurance to stand up to the cassoulet.

After the cassoulet is a clean green salad of romaine, fortified with slightly biting, pale green and white leaves from the heart of chicory. The salad is dressed with a simple vinaigrette reinforced with a bit of mustard. Dessert is a marvel of lightness, a cold orange-hazelnut souffle' infused with fresh juice and the flavor of Frangelico, the sublime Italian liqueur that is a sweet essence of hazelnuts. The souffle', served either in hollowed-out orange shells or a souffle' dish, is garnished with whipped cream, candied orange peel and chopped toasted hazelnuts.

While long cooking times are involved, making a cassoulet is not complicated. Certain elements are combined and allowed to simmer. Then another group of ingredients is prepared and cooked separately. Finally the dish is assembled and baked. All steps can be done at various times starting at least two days before the cassoulet is to be served. First, the beans--and great northern beans are best--must be soaked overnight. The following day, the beans and meats are cooked and the cassoulet is put together and refrigerated. On the day of the party, the only thing left is to bring the cassoulet to a simmer on top of the stove and then put it in the oven for its final cooking.

As in all good peasant dishes, the ingredients of a cassoulet are variable, to a point, depending on what is available at the time. Beans are a given, as are certain meats--salt pork, sausages, lamb and/or pork, along with tomatoes in some form, onions, garlic and other seasonings. The fresh pork or ham rind that was thought to be essential has become next to impossible to find, since the rind is mercilessly trimmed off by packers before they encase their meats in vacuum-plastic wrappers. Those fortunate enough to have access to fresh rind should add a pound of it to the beans along with the salt pork and sausages. The cooked rind is then cut into one-inch squares and combined with the other meats.

Another optional ingredient is preserved goose or duck, also called confit, whose presence in a cassoulet is viewed as critical in some regions of France and quite unnecessary in others. The lack of preserved goose or duck should never stop a cook from making a cassoulet, but its presence certainly adds much.

Since goose is such a luxury in this country, duck becomes the bird of choice. Some recipes suggest roast or broiled duck as an alternative for the confit, but the flavor is undistinguished compared to the real thing. If preserved duck is used, the cassoulet will, of course, be much richer and feed more people or yield more leftovers--a plus, since cassoulet reheats well, needing only the addition of a little stock. It also can be frozen for at least a month.

Confit is made by marinating cut-up duck in a salt and spice mixture for 24 hours and then cooking the pieces slowly in rendered fat. The duck will keep for at least three months under refrigeration if it is completely covered by fat. I have been able to keep confit longer if I take the extra step of straining the fat through several layers of cheesecloth after the duck has cooked in it.

Ideally, the fat comes from the duck, but even our fat-laden American ducks do not have enough for this dish. Chicken fat or fresh pork fat--fatback or fat from pork loins--can be used to make up the required quantity. Fresh pork fat can be difficult to come by, for the same reason that pork rind is. I use chicken fat, which is often available frozen in supermarkets. The chicken backs I buy for making stock are an even more reliable source of chicken fat, the globules of which can be pulled out and stored in the freezer before the stock is made.

The fat must be rendered before it is used. One pound of fresh fat will yield about two cups or more or rendered fat, and once rendered will keep for at least three months under refrigeration. The cut-up fat is placed in a heavy pot with a little water, which evaporates during the cooking, and simmers slowly over very low heat for about an hour. Halfway through the cooking the fat loses its odd smell and when it is finished is a lovely clear yellow. (When congealed, the fat turns white.) The cracklings are a medium brown but become a rich brown as they continue to cook in the hot fat even when the pot is removed from heat.

Some think that the cracklings are the best part of rendered fat, particularly when they are reheated in a frying pan for about 15 minutes to recrisp them, sprinkled with a little salt and served with drinks. Cracklings keep for a few days under refrigeration and freeze well.

Temple oranges, which are in season during the winter, are wonderful for the orange-hazelnut souffle'. The juice is very good and they are easier to gut than navel oranges. It is worth the bother of digging out the flesh and juice just to have the shells in which to pack the souffle'. An easier and perfectly acceptable alternative is to present the dessert in a souffle' dish. Frangelico can be found in half bottles at most liquor stores for about $10. Considering its deliciousness and how far a little goes, it is well worth the price. PRESERVED DUCK 4 1/2 to 5 pound duck, defrosted if frozen, fat and fatty pieces of skin removed and reserved, and wing tips, liver, gizzard and neck reserved for another use 5 1/2 tablespoons coarse salt 1/4 teaspoon thyme 1/2 bay leaf, crumbled Pinch allspice About 3 pounds unrendered chicken fat or fresh pork fat (fatback or fat from pork loins) or enough to make 7 cups of fat in all--unrendered duck fat reserved from duck plus chicken fat or pork fat 1/2 cup cold water

Cut the duck into serving pieces. Detach the wings and cut each breast in two. Detach the thighs from the legs.

Mix the salt, thyme, bay leaf and allspice and rub all over the duck pieces. Place the duck in a bowl, cover with plastic wrap and refrigerate for 24 hours, no longer. Rinse the duck pieces well under cold running water and dry thoroughly, preferably with a cloth towel.

The fats can be rendered any time while the duck is marinating. Using kitchen shears, cut the duck fat, the fatty skin and the chicken fat, if used, into 1/4-inch pieces. With a chef's knife, cut the pork fat into a 1/4-inch dice. Place all the fats in a 4- or 5-quart heavy pot or enamel on iron casserole and add the water. Place over low heat and cook, barely at a simmer, for about an hour, or until the fat is clear and the cracklings have taken on a medium-brown color. Set away from heat for half an hour. The cracklings will continue to brown as the fat cools. Set a large strainer over a bowl and pour the fat through it. Reserve the cracklings, which can be refrigerated for a few days or frozen for longer. Cover the bowl of fat and when it is completely cool, refrigerate.

To make the confit, place the rinsed and dried duck pieces into a clean 5-quart heavy casserole. Melt the rendered fat if it has congealed and pour it over the duck. The fat should cover the duck completely. Cover the casserole and place in a 225-degree oven for 2 hours, or until the duck is tender and completely cooked. Remove the duck pieces to an earthenware crock or bowl. Place a strainer over a bowl, line the strainer with a few thicknesses of cheesecloth and pour the fat through it. Then ladle the strained fat over the duck, which must be completely covered by the fat. As the fat congeals, submerge any parts of the duck that may have floated to the surface. When the fat is completely cooled, cover the crock or bowl with foil and refrigerate. The preserved duck can be used within a few days and will keep under refrigeration, if it is completely covered with fat, for at least three months.

When the duck is to be used, let it sit at room temperature for two or three hours to soften the fat. Remove the pieces and brown them lightly in a frying pan in some of the fat. The fat can be frozen and reused when needed to make more preserved duck. CASSOULET (8 to 12 servings) 2 pounds dried great northern beans 1/2-pound piece lean salt pork 1 large onion, halved 2 medium carrots, scraped, in 1/2-inch slices 1 stalk celery with leaves in 1/2-inch slices 2 large cloves garlic 4 sprigs parsley 3 whole cloves 1 bay leaf 1/2 teaspoon coarsely crushed black pepper 1 teaspoon thyme 4 13 1/2-ounce cans chicken broth plus enough water to cover the beans 1 pound hot Italian sausages 2 tablespoons fat from the preserved duck, if used, or rendered chicken fat or lard or shortening 1 pound boned shoulder of lamb, in 2-inch chunks 1 pound lean pork, in 2-inch chunks 1 large onion, minced 2 large cloves garlic, minced 1 1/2 pounds ripe tomatoes, or enough to make 2 cups peeled, seeded and chopped, or 2 cups drained canned Italian tomatoes 1 cup dry white wine 1 teaspoon salt Freshly ground pepper to taste 4 1/2- to 5-pound preserved duck (optional, see recipe above) 2 cups fresh bread crumbs 1/2 cup minced parsley 4 tablespoons fat from the confit or rendered chicken fat (optional) Additional canned chicken broth, if needed

Soak the beans overnight in a large pot of cold water. Cook the salt pork in 2 quarts of boiling water for 15 minutes, drain, rinse with cold water, dry and set aside. Cut two large pieces of cheesecloth to make spice bags and divide between them the halved onion, the carrot and celery slices, garlic, parsley, cloves, bay leaf, crushed pepper and thyme. Tie securely into bags with kitchen twine.

Drain the beans and rinse them under cold running water. Place the beans in an 8-quart pot and add the salt pork, the spice bags, the 4 cans of chicken broth and enough cold water to cover the beans. Bring to a boil slowly, simmering until no scum remains. Reduce heat and simmer for 1/2 hour. Add the sausages and simmer for 1 hour more, or until the beans are tender but not mushy.

While the beans are cooking, heat the duck fat, chicken fat, lard or shortening in a large saute' pan or frying pan. Brown the lamb and the pork, a few pieces at a time, removing them to a bowl as they are done. When all the meat is browned, return the pieces to the pan and add the chopped onion and minced garlic. Saute', stirring, for 5 minutes. Add the tomatoes, white wine, salt and pepper. Cover and simmer for 1 hour, stirring occasionally.

When the beans are cooked, discard the cheesecloth bags and remove the salt pork and sausages. Cut the salt pork into 1-inch chunks. Slip the casings off the sausages and discard the casings. Then slice the sausages into 1/2-inch pieces. Add the salt pork and sausage pieces to the lamb and pork mixture and mix well. Lightly brown the preserved duck, if it is used, in a bit of its own fat in a frying pan. Set aside.

To assemble the cassoulet, drain the beans into a colander set over a bowl and reserve the bean liquid. Place a 1-inch layer of beans on the bottom of an 8-quart casserole, preferably one made of enamel on cast iron. Arrange half the meat mixture and half the duck, if used, on the beans. Then add another layer of beans and a layer of the remaining meats and duck. Finish with a third layer of beans. Ladle on as much of the bean liquid as needed to cover the meats and the beans. Reserve any remaining liquid. Should there not be enough liquid, use more canned chicken broth to cover the mixture.

Mix the bread crumbs with the parsley and cover the beans evenly. Drizzle the duck or chicken fat, if it is available, over the crumbs. Bring the casserole to a simmer on top of the stove. Cover and place in a 300-degree oven for 1/2 hour. Remove the cover, raise the oven temperature to 350 degrees and bake for another hour. The reserved bean liquid (or more chicken broth) can be used to moisten any leftover cassoulet when reheating. Should the cassoulet seem dry or the liquid very thick when it is in the oven, add a bit more bean liquid or chicken stock. COLD ORANGE-HAZELNUT SOUFFLE (8 servings) For the presentation: 8 medium-large temple or navel oranges, or a 1-quart souffle' dish For the cold souffle': 3/4 cup plus 1 tablespoon fresh orange juice 1 1/2 tablespoons (1 1/2 envelopes) unflavored gelatin 4 eggs, separated 3/4 cup sugar 1 tablespoon Frangelico (Italian hazelnut liqueur) 1 cup heavy cream For the garnish:

Peel of two temple or navel oranges, removed in a fine julienne with a zester, or removed with a potato peeler and then cut into a fine julienne 1 cup sugar 1/2 cup water 3/4 cup heavy cream 2 teaspoons sugar 1 teaspoon Frangelico 1/3 cup (1 1/2 ounces) hazelnuts

First prepare the orange shells or the souffle' dish, whichever is to be used for the presentation. For the shells, cut off the top quarter of each orange. Hold the orange over a bowl and with a teaspoon scoop out the flesh and juice into the bowl. Strain the contents of the bowl and measure out the juice needed for the souffle'. Then, with the fingers, carefully pull out the pulp from each shell to make a smooth interior. To prepare the souffle' dish, cut a piece of foil an inch or so greater than the circumference of the dish. Fold the foil in half lengthwise and wrap it around the dish. Fasten the ends with transparent tape and then secure the foil around the dish with a rubber band. Lightly oil the inside of the foil that stands above the dish with peanut oil or any other unflavored cooking oil. Set aside.

To make the souffle' mixture, place 1/4 cup of the orange juice into a metal cup and sprinkle gelatin over it. When the gelatin has softened, place the cup in a small frying pan of water and heat until the gelatin is completely dissolved. Turn off the heat but let the cup sit in the water.

Combine the egg yolks and sugar in a bowl and beat with an electric mixer until very light. Then beat in the remaining orange juice, the tablespoon of Frangelico and the dissolved gelatin. Set aside.

In a clean bowl and with clean beaters, whip the egg whites until they are stiff but not dry. In another bowl, whip the cup of heavy cream until stiff. Fold the orange mixture into the egg whites and next fold in the whipped cream. There will be about 6 cups of the souffle' mixture in all. Spoon the mixture into the orange shells, mounding the tops and smoothing them, or pack into the souffle' dish. Refrigerate overnight.

Prepare the candied peel and the toasted hazelnuts the day before. Cook the peel in a quart of boiling water for 10 minutes. Turn into a strainer and rinse the cooked peel under cold running water. Pat dry on paper towels and set aside.

Place the sugar in a small, heavy saucepan and shake the pan so the sugar makes an even layer. Slowly pour the half cup of water into the pan. Place over medium heat, stirring carefully until the sugar is dissolved. Heat the syrup to 238 degrees on a candy thermometer and immediately add the blanched peel. Cook for another two minutes, stirring constantly. Set aside for 5 minutes. Turn the peel into a strainer and discard the syrup. Refrigerate the peel until needed.

To prepare the hazelnuts, turn them into a cake pan in one layer and place in a 425-degree oven (or toaster oven) for 10 minutes. Turn the nuts onto a cloth towel, gather the towel up around them and rub the nuts together to remove their skins. A few bits of stubborn skin can be picked off or allowed to remain. Chop the nuts coarsely on a board with a knife. Set aside.

Assemble the dessert an hour before guests arrive. Whip the cream for the garnish with the sugar and Frangelico, turn into a pastry bag with a #2 star tube and pipe a border of cream around the circumference of each orange. Or, if a souffle dish is being used, carefully remove the collar and pipe a border of cream around the souffle plus spokes across the top. Place some candied peel in the center of each orange, inside the cream border, or within the spokes on the souffle dish. Sprinkle the chopped hazelnuts over the peel. Refrigerate until served.