NOW THAT a low-sodium diet book has made the best-seller list hosts can feel chic as well as virtuous about serving low-sodium food atholiday parties.

This is good news for those on special diets, who usually must forego groaning boards full of culinary temptations each holiday season. And it's also good news for the host who, smitten with holiday good will, really wants to accommodate his friends on restricted diets without making it appear that he's gone to a lot of trouble to do it.

The truth is, many hosts are anxious to camouflage "diet" fare in party food garb, but don't know exactly how to go about it. At worst, they serve the same old dishes and leave it up to the guest to pick and choose. Or, they may think that prepared foods from the special diet section of the supermarket are the only choice.

Not so, says Michael Stong, a low-sodium dieter for seven months who got fed up with canned low-sodium soups about two weeks into his diet. His description of some prepared low-sodium products in the supermarket is "awful." He maintains, however, that low-sodium cooking needn't reproduce the dismal alternatives offered by manufacturers.

The Vienna, Va., resident, who calls himself a "big eater," celebrated his first low-sodium Thanksgiving with a hearty meal of traditional dishes: homemade cranberry sauce; frozen turkey breast (with no sodium used in processing); a "cream gravy" made from whole milk, butter, chopped mushrooms, low-sodium bouillon, sage, poultry seasoning and onions; a traditional turkey stuffing made from low-sodium bread; mashed potatoes, which he says are "exceedingly low" in sodium and should be served with the turkey gravy; broccoli with cheese sauce made from low-sodium cheese; and an apple butter bread made with low-sodium baking powder.

To the relief of many hosts, some of the special ingredients needed to make these foods can be found in regular supermarkets. While regular cheese is prohibited on a diet of restricted sodium, low-sodium colby and an acceptable cheese called "lorraine swiss" are not uncommon in area supermarkets. The low-sodium dieter needs to shop around, says Stong, to find out who has what. Someone doing just one low-sodium meal will probably find one or two stops sufficient.

Unfortunately, low-sodium baking powder is not so easy to find, but Rockville's Low Sodium Pantry carries it, as do local health food stores. Janet Tenney of the consumer affairs department of Giant Foods says Giant just doesn't see a market for it. But many supermarkets carry a diversity of low-sodium products; many, but not all, are found on shelves stocked with foods for special diets. Sodium-free bouillon is readily available, as are low-sodium canned tomatoes and cheese. Other foods, such as pasta and frozen vegetables, are naturally low in sodium and generally aren't sold in a special diet section.

As for converting recipes to use low-sodium baking powder, Stong offers two pieces of advice: The amount needs to be increased 1 1/2 to two times (using two teaspoons of low-sodium powder to every one of conventional, double-acting powder), and it is necessary to work very quickly once the baking powder is in the batter, as it begins to react immediately.

One word of caution before embarking on this type of cooking -- a low-sodium diet is not a low-calorie diet.

The following recipe for apple butter bread yields a product that is very dense and takes well to a generous soaking in bourbon or brandy as it comes from the oven. APPLE BUTTER BREAD (one 8-by-4 1/2-inch loaf) 1/2 cup unsalted butter 2 eggs 1 cup sugar 2 cups all-purpose flour 1/2 teaspoon nutmeg 1 teaspoon cinnamon 2 teaspoons low-sodium baking powder 1 cup any commercial apple butter 1 cup raisins 3/4 cup chopped nuts

Grease and flour a bread pan. Melt the butter over low heat. Beat the eggs in a bowl. Beat in sugar and melted butter. Stir in flour, nutmeg and cinnamon. Quickly stir in baking powder. Stir in apple butter, raisins and nuts. Pour into prepared bread pan. Bake 1 hour at 350 degrees without opening the oven. Test for doneness. If it looks too brown but needs more cooking time, cover with foil. May require 15 minutes more baking time. CHICKEN STROGANOFF (4 servings) 1 large onion, sliced 1 cup fresh mushroooms 3 to 4 cloves garlic, minced 1 green pepper, sliced 2 tablespoons vegetable oil or unsalted butter 2-ounce jar chopped pimientos 4 chicken breasts 2 teaspoons low-sodium chicken bouillon 1 1/2 cups water 8 ounces plain yogurt or sour cream Freshly ground pepper to taste

Cook onion, mushrooms, garlic and green pepper in vegetable oil over medium heat in a wide flameproof casserole until green peppers have softened. Add pimiento, chicken breasts in one layer, bouillon and water. Cover the casserole and place in a 350-degree oven for 45 minutes or until meat is done. Transfer meat from casserole to a platter and reduce the liquid in the casserole over high heat until only a few tablespoons remain. Turn the heat to low and add yogurt and black pepper. When chicken is cool enough to handle, remove skin and bones from chicken breasts. Chop meat and add to sauce in casserole. Serve over rice or a mixture of green and yellow pasta. LOW-SODIUM SQUASH CASSEROLE (6 servings) 3 medium yellow squash (or substitute zucchini), sliced 2 medium onions, sliced 3 slices low-sodium bread, blended into crumbs (or use prepackaged salt-free matzo crumbs) Coarsely ground pepper to taste 1 pound canned low-sodium tomatoes 3 to 4 ounces low-sodium cheese (colby or lorraine swiss)

In a lightly greased, 9-by-9-inch casserole, layer squash, onion and bread crumbs. Sprinkle each layer with pepper. Drain about half the juice from the tomatoes and place contents of can into blender. Blend at low speed for a couple of seconds to make a lumpy sauce. Pour tomato mixture over squash layers and top with cheese. Cover with foil and bake at 350 degrees for 30 minutes. Uncover and bake 30 minutes more.

Note: You may want to add a little minced garlic, basil or oregano to this dish. For a main dish, add a layer of browned ground beef or cooked chicken.

The following recipes come from Eleanor Brenner's book "Gourmet Cooking Without Salt." The pa te' is rather crumbly when cold, but will make an excellent addition to a cocktail buffet. Offer low-sodium melba toast and the mustard recipe to follow. Or, stuff mushrooms with the mixture and bake. Serve them warm with the mustard as a dip. PATE CHAUD (1 large loaf) 1 1/2 pounds lean chuck, very finely ground 1 1/2 pounds lean ground veal or chicken 8 cloves garlic, pressed 1/3 cup very finely minced onion 1/4 teaspoon ground red pepper 2 teaspoons salt-free chili powder 1 teaspoon dried cumin 1 teaspoon dried sweet basil 1/4 teaspoon dried marjoram 1/4 teaspoon dried oregano 1/2 teaspoon dried thyme 1/2 teaspoon dried tarragon 1 teaspoon dried chervil 1 tablespoon seasoned salt substitute (optional) 1 1/2 teaspoons freshly ground black pepper 6 tablespoons clarified butter (see note) 1 cup strong beef stock (see recipe) 3 tablespoons dry sherry 1/4 cup brandy

Place the meat, garlic, onion, red pepper, chili, cumin, basil, marjoram, oregano, thyme, tarragon, chervil, salt substitute, pepper and clarified butter in a bowl. Mix thoroughly until all ingredients are blended. Add the beef stock, a little at a time, mixing constantly, until the mixture is blended. Stir in the sherry and brandy. Spoon the mixture into a well-buttered 2-quart ovenproof crock (or bread pan). Cover tightly. Set the crock in a baking pan and pour enough boiling water to come up to 2/3 the height of the crock. Bake 1 1/2 hours at 300 degrees. Increase heat to 350 degrees. Uncover and bake for 45 minutes or until the pa te' is browned on top. The pa te' may be served from the crock or unmolded, sliced and arranged on a preheated platter.

Note: To clarify butter, heat it in a heavy saucepan over very low flame. Skim any foam from the top. When there is clear liquid on the top and a white or brown residue on the bottom, remove it from the flame. Pour off the clear liquid and save for pa te'. Discard residue. SZECHUAN FLOUNDER (8 servings) 4 pounds flounder fillets, cut into 2-by-4-inch strips 1/4 cup fresh lemon juice 1/4 cup dry sherry 4 tablespoons hot pepper oil (found in Chinese markets) 6 cloves garlic, finely minced 1 large bermuda onion, sliced paper thin 1 1/2 inches ginger root, finely minced 1-pound can unsweetened peaches, drained and pure'ed 1 cup apricot pure'e (see note) 1/3 cup rice vinegar 1/3 cup dry sherry 1/2 cup brown sugar 1/4 teaspoon ground red pepper 1 tablespoon cornstarch 3 scallions, sliced into paper-thin rings

Place the fillets in a plastic bag. Pour in the lemon juice and sherry, seal tightly and refrigerate. Marinate at least 2 hours, turning the bag once or twice. In a large, heavy skillet, heat the pepper oil over a high flame and stir-fry garlic and onions until onions are translucent. Add the ginger and stir-fry 1 minute. Stir in the peaches, apricots, vinegar, sherry, sugar and ground red pepper. Cook for 3 minutes. Add the cornstarch and stir constantly until the sauce starts to thicken. Reduce the flame to low and cover the skillet. Cook 15 minutes.

Drain the fillets and pat dry between a double thickness of paper towels. In a large, ovenproof casserole, spoon in a fourth of the sauce. Place some fillets on top, then repeat until all the ingredients are used. End with a layer of sauce. Bake 12 to 15 minutes at 550 degrees or until the fish flakes easily to the touch of a fork.

To serve, form a ring of rice on a large platter. Spoon the fish and sauce into the center of the ring and garnish with sliced scallions.

Note: To make pure'e, place 1/2 pound of dried apricots in a bowl. Pour 1 1/4 cups boiling water over them and cover the bowl with aluminum foil. Allow to soften until needed in the sauce. Pure'e in blender and measure 1 cup. CHICKEN WITH ALMOND SAUCE (4 servings) 2 chicken breasts, halved and boned 1/2 cup lemon juice, divided 1 tablespoon olive oil 2 medium onions, chopped 2 tablespoons almonds, coarsely chopped 2 tablespoons all-purpose flour 1/2 cup dry red wine 1/2 cup water 2 tablespoons heavy cream 4 teaspoons low-sodium chicken bouillon Black pepper to taste 1 teaspoon garlic powder 1/8 teaspoon ground mace 1 teaspoon chopped parsley 1/4 teaspoon thyme

Place chicken in roasting pan, skin side down. Pour on half the lemon juice. Cover and bake 20 minutes. In a saucepan, heat oil. Saute' onions until golden. Add almonds and saute' 2 minutes. Stir in flour to blend well. Slowly add wine, water and cream, stirring constantly. Stir in bouillon, spices and herbs. Cook over low heat 5 minutes. Set sauce aside. Turn chicken skin side up. Cover with remaining lemon juice and bake, uncovered, 20 minutes, or until browned. Pour almond sauce over chicken breasts and bake 10 minutes, uncovered, or until sauce is bubbly. Serve with rice. From "Tasting Good: The International Salt-Free Diet Cookbook," (Bobbs-Merrill, $14.95). SWEET MUSTARD (1 1/2 cups)

The following recipe, from "Craig Claiborne's Gourmet Diet," (Ballantine, $2.95), is a rather nice attempt at duplicating sweet-hot European mustard. Serve it with sliced meats or spread it on chicken before baking or broiling. 1/4 cup whole mustard seeds 6 tablespoons dry mustard 1 teaspoon dried tarragon 1 1/4 cups boiling water 1/2 cup tarragon vinegar 1/2 cup dry white wine 1 tablespoon peanut or vegetable oil 1/4 cup sugar 1/2 cup finely chopped onion 2 teaspoons finely minced garlic 1/4 teaspoon ground allspice 1/4 teaspoon ground cinnamon 1/4 teaspoon ground cloves

Combine the mustard seeds, dry mustard, tarragon and water in a small bowl. Allow to stand for 1 hour. Meanwhile, combine the vinegar, wine, oil, sugar, onion, garlic, allspice, cinnamon and clove in a saucepan. Bring to a boil and simmer 5 minutes. Pour the mixture into the bowl of a food processor or electric blender. Add the mustard mixture and blend about 2 minutes. Spoon and scrape the mixture into a saucepan set in a larger pan of boiling water or into the top of a double boiler. Cook, stirring often, for about 5 minutes. As the mixture cooks, be sure to scrape around the inside of the saucepan with a rubber spatula so that the entire mixture cooks evenly. Scrape the mustard into a mixing bowl and set aside to cool. Store in sealed jars and refrigerate.

Note: To make ballpark mustard, add a teaspoon of turmeric to the first mustard mixture.