The pop of the cork, the enticement of bubbles rising lazily to the surface, the tickle to the nose before the first sip -- everything about champagne adds up to a sense of celebration. No wonder that, according to a recent survey, 96 percent of the French regard champagne as indispensable to a special occasion.

One reason that I've recently become a fan of champagne is the personal discovery of an inexpensive substitute, sparkling wine, the best of which is made by the same me'thode champenoise as champagne. From Europe come sparkling Loire vouvray, cremant from Burgundy and the famous Italian asti spumante, which is on the sweeter side. California calls all of its sparkling wines "champagne," and wine expert Hugh Johnson says that some of the best me'thode champenoise wines are produced in that state.

Be it champagne or a close relation, a bottle of sparkling wine makes the smallest gathering an occasion, whether a celebration of Valentine's Day, or a visit by old friends. Keeping tune with the mood, this menu includes smoked salmon, the finest of steak and, for dessert, a souffle', all at surprisingly modest cost.

Plain smoked salmon comes dear, but as the principal ingredient in pa te', a little goes a long way. Hot- or cold-smoked salmon, or lox, can be used in this recipe. Be on the lookout for pieces and trimmings, which can be a real bargain. Another advantage of pa te' is the chance to adjust the quality of the salmon. If the fish is salty, for instance, be sure to use unsalted butter and add no extra salt when seasoning. If the salmon is oily (common with lox), cut down on the butter and add plenty of lemon juice.

The essence of luxury, cha teaubriand is a cross between a roast and a steak, cut from the center of the filet and serving two people. It must be specially ordered from your butcher or, if you prefer, you can economize by preparing the meat yourself, as explained later. The instructions explain how to cut and shape a "double" cha teaubriand to serve four instead of two from a single filet of beef. Cha teaubriand can be roasted, but I like to broil it so it remains rare with a charred surface.

Classic accompaniment to cha teaubriand is bearnaise sauce and this recipe is a little different -- a light version in which butter is replaced by yogurt. Basis for the sauce is the traditional reduction of white wine, wine vinegar, shallot and tarragon, which is whisked to a light mousse with egg yolks. Yogurt is beaten in instead of melted butter to make a sauce very similar in texture to classic bearnaise, but lighter and slightly tarter in taste; I've become quite addicted to it.

Steak calls for baked potato and why not, unless you feel strongly that you prefer something green? The smaller idaho bakers now available are a realistic serving size, taking about 45 minutes to cook in a 400-degree oven. Simply rinse them, roll them in salt and prick them so they don't explode in the oven. The brown skin of the potato is, I think, the best part, and I often deliberately overcook them so the skin is extra crisp, an excellent foil for bearnaise.

It isn't easy to flavor a souffle' with pears, for a souffle' base must have body to hold the whipped egg whites, whereas a good pear consists mainly of juice. The solution adopted by this recipe is to add ground toasted hazelnuts, an inspired combination. Otherwise the souffle' is straightforward enough; pear pure'e and ground nuts, beaten into a light pastry cream, form the base. After whipping, the egg whites are beaten with a little sugar to make meringue so that they will hold up well for folding into the pear base.

The books tell you to bake a souffle' at once, but I've found that, provided the mixture holds its shape and has not been overfolded, it can wait for an hour in the refrigerator without harm. Speaking as cook/hostess, I'm more than willing to take the risk if I'm spared the effort of whisking egg whites in the middle of dinner. However, once a souffle' is in the oven, the cook is on countdown for optimum launching to the table. Like a burning rocket, a hot souffle' cannot be delayed. Timetable

When cooking for four people, complicated advance preparation is unnecessary. Here the appetizer can be prepared several days ahead and everything else is done in the evening before dinner.

Up to four days ahead: Make salmon pa te', seal with clarified butter and refrigerate.

Up to 4 hours ahead: Prepare cha teaubriand for broiling and store in refrigerator. Scrub potatoes, prick with a fork and rub with salt. Make base for pear and hazelnut souffle' and refrigerate. Set the table. Chill the champagne.

1 1/2 hours before serving: Heat oven to 400 degrees and bake potatoes. Take pa te' from refrigerator and leave at room temperature.

40 minutes before serving: Take out potatoes, light the broiler.

30 minutes before serving: Broil cha teaubriand. Make light be'arnaise sauce and keep warm in water bath.

15 minutes before serving: Whip egg whites and complete souffle' mixture; store in refrigerator. Make whole-wheat toast and decorate pa te' with lemon slices.

Just before serving: Take out cha teaubriand, cover with foil and keep warm. Turn oven heat to 425 degrees for cooking souffle'. Reheat potatoes briefly in oven.

After serving appetizer: Carve cha teaubriand and serve with potatoes and be'arnaise sauce. Cook the souffle'. SMOKED SALMON PATE (Pa te' de Saumon Fume') (4 servings)

If you use hot-smoked salmon, which is already fully cooked, reduce cooking time in this recipe to 1-2 minutes. However, do not omit the cooking step altogether, as the butter and water moisten the salmon and make it easier to pure'e. 1/3 cup butter 6 ounces hot- or cold-smoked salmon, chopped 3-4 tablespoons whipping cream Pepper to taste Pinch cayenne Juice 1/2 lemon Salt (optional) 1 lemon (for decoration) 8 slices toasted whole-wheat bread (for serving)

In a small skillet melt 2 tablespoons of the butter. Add smoked salmon, 3 tablespoons water and cook over low heat until salmon flakes easily, 1-2 minutes for hot-smoked salmon, 3-5 minutes for cold-smoked salmon or lox. Leave mixture to cool slightly.

Cream remaining butter in a food processor or in an electric mixer with the pastry paddle. Add salmon mixture and cream and work to a pure'e. Season pa te' to taste with pepper, cayenne and lemon juice. Add salt only if needed.

Spoon pa te' into a crock or individual ramekins and chill. Pa te' can be made up to 48 hours ahead, covered, and refrigerated. Leave it at room temperature 2-3 hours to soften before serving.

To decorate: Notch the lemon with a citrus stripper. Halve lemon lengthwise, then cut crosswise in thin slices. Decorate crock or ramekins with slices. Serve pa te' with hot toast.

Tip: To double the keeping time of pa te's, pack tightly in a crock to exclude all air. Smooth the surface and cover with a 1/4-inch layer of melted clarified butter and refrigerate. The butter will set and seal the pa te'. CHATEAUBRIAND (4 servings)

Cooking time is the same for one "double" or two small cha teaubriand steaks. One 2-2 1/2-pound chateaubriand steak (see below) 5-6 tablespoons butter Salt and pepper to taste Bunch watercress

Light the broiler. Spread meat with butter. Sprinkle with salt and pepper and set on a rack in the broiler pan.

Broil the meat, setting pan 3 to 4 inches from the heat so meat browns and chars slightly, but does not burn during cooking. Allow 10 to 12 minutes cooking on each side and baste often during cooking with pan juices.

Transfer beef to a carving board, cover loosely with foil and let stand 5 to 10 minutes so juices are evenly distributed before carving.

Remove strings and carve meat in 3/4-inch diagonal slices and arrange on a platter or individual plates. Serve each person with some of the brown outside and the rare center and garnish plates with watercress. Preparing Chateaubriand

Buy a whole untrimmed beef filet and trim off the "chain," the small loose strip that runs the length of the meat; this is tough and could be used for soup or, if carefully trimmed, for kebabs.

Trim all gristle and sinew from the filet (leaving a little fat to add richness), then weigh the meat (filets can vary a good deal in size).

Cut filet in two pieces so the thinner, pointed half weighs between 2 and 2 1/2 pounds. Keep the thicker end for steaks or to roast another time. The thin end makes a "double" cha teaubriand to serve four.

To shape it, fold the pointed, tail end of the meat over on itself to form an even cylinder about 9 inches long. Tie the meat neatly in shape with string, including two lengthwise strings to prevent it curling out of shape during cooking.

Tip: When trimming meat, remove all gristle and sinew, but leave a little fat for flavor and richness. LIGHT BEARNAISE SAUCE (Sauce Be'arnaise Le'ge re) (Makes 1 1/2 cups sauce for 4-6 servings)

An inspiration of the new French cooking, this light bearnaise sauce uses yogurt instead of butter. 3/4 cup plain low-fat yogurt 4 tablespoons white wine vinegar 4 tablespoons white wine 2 shallots, finely chopped 1 tablespoon chopped fresh tarragon or tarragon leaves preserved in vinegar 3 egg yolks Juice of 1/2 lemon Salt and pepper to taste

Whip yogurt until smooth. In a small heavy saucepan combine vinegar, wine, shallots and tarragon. Boil until reduced to 1 tablespoon and let cool.

Whisk in egg yolks and continue whisking until mixture is pale, 30 seconds. Set pan over low heat and whisk constantly until mixture is creamy and thick enough for the whisk to leave a trail on base of pan. This should take 2-3 minutes; the base of the pan should be quite warm but never burning to the touch, or the mixture may separate.

Remove from heat and whisk in yogurt a tablespoon at a time. Do not add yogurt too quickly or sauce may curdle. Season to taste with lemon juice, salt, and pepper.

The sauce can be made up to 30 minutes ahead and kept warm in a water bath, but it should never be hotter than tepid or it will curdle. PEAR AND HAZELNUT SOUFFLE (Souffle' de Poires aux Noisettes) (4 servings)

Toasting hazelnuts develops their flavor and loosens the dark skin that is often left after shelling. If hazelnuts are not available, almonds may be substituted. Butter for souffle' dish 1/2 cup hazelnuts 2/3 cup milk 2 eggs, separated 3 tablespoons granulated sugar 2 tablespoons flour 1 large ( 1/2 pound) ripe pear 2 egg whites 1 tablespoon confectioners' sugar

Thickly butter a 1-quart souffle' dish, making sure edge is buttered so mixture does not stick. Heat oven to 350 degrees and toast hazelnuts in oven until brown, 12-15 minutes. If hazelnuts were unpeeled, rub off skins with a cloth. Let nuts cool, then grind until fine in a food processor or in a cheese mill.

In a saucepan, scald milk. Beat egg yolks with half the granulated sugar until thick and pale; stir in the flour. Whisk in the hot milk, return mixture to the pan and bring to a boil, whisking constantly until custard thickens. Cook over low heat 2 minutes, whisking constantly. Let custard cool slightly, then stir in ground hazelnuts.

Peel and core the pear. Grind to a coarse pure'e in a food processor or chop very finely with a knife. Stir into souffle' mixture. Work quickly as the pear will discolor. Pear and hazelnut souffle' can be prepared 3-4 hours ahead to this point. Rub surface of mixture with a lump of butter to prevent a skin forming, cover with plastic wrap and refrigerate.

To finish: Heat oven to 425 degrees. Whip egg whites until stiff. Add remaining granulated sugar and continue beating 20 seconds to make a light meringue. Heat pear mixture until hot to the touch. Remove from heat and stir in about a quarter of the meringue mixture. Add this mixture to remaining meringue and fold together as lightly as possible. Spoon into prepared souffle' dish. The prepared souffle' can be stored up to 30 minutes in the refrigerator.

To finish: Bake souffle' in a 425-degree oven until puffed and browned, 15-18 minutes. Sprinkle with confectioners' sugar and serve immediately.