Sunday is a day devoted to hearts, which can be in your mouth, on your sleeve or in the right place, but which certainly, come Valentine's Day, should be joined by a Significant Other. Or, if that Other has not yet appeared, by loving friends.

It is traditional to celebrate with heart-shaped chocolates but as Ogden Nash has pointed out, " . . . liquor is quicker," and a good Sauternes or auslese is sweet as well. Stick one red rose in a vase, put a love song on the phonograph and give a Valentine's Day party featuring desserts and dessert wines.

Champagne will do, but it is more interesting to experiment with some wines produced by what the French call pourriture noble, noble rot. Sweet wines come from grapes which have been left on the vine until they are overripe; the skins shrivel, the water content is reduced and the sugar content increases. During this time the grapes of the Sauternes and some of the Rhine vineyards are attacked by the benevolent mold, Botrytis cinera, which gives them their unique bouquet.

Wines produced in the Sauternes region of France are sold under either the name Sauternes or Barsac, the latter being a commune in the Sauternes region which can use either designation and produces wines which are usually a bit less sweet than Sauternes.

The sweet wines of Germany ascend from spatlese through auslese, beerenauslese and, sweetest of all, Trockenbeerenauslese. Both Germany and California also produce small quantities of ice wine, made from grapes which have frozen on the vine, leaving a high concentration of sugar.

Some wines to sweeten Valentine's Day:

Fred Gordon at Morris Miller, 7804 Alaska Ave. NW (723-5000) recommends a Chateau Climes, Premier Cru Sauternes-Barsac, 1976, for $16.99; a Chateau Sigalas Rabaud, Premier Cru, 1967, $27.50; and an Oppenheimer Sacktrager Beerenauslese, $21.99.

At MacArthur Liquors, 4877 MacArthur Blvd. (338-1433), Elliott Staren suggests either a Dom Scharzhofberger, Spatlese, 1975, $7.99, or a 1976 Chateau Filhot, Sauternes, at $11.95.

Mary Combemale at Mayflower Wines & Spirits, 2115 M St. NW. (463-7950) would celebrate with Chateau du Cros, Loupiac, 1976, "a Bordeaux which drinks like a Sauternes though not as fat," for $7.99; Chateau de Sesle, 1979, a sweet table wine from the Loire at $10.99, or a Beerenauslese, Niersteiner Hipping, 1976, at $12.49.

The spirit of romance could be fed with Kiss-Me-Quick Pudding or Love and Tangle, recipes for both of which are below and are taken from Andre L. Simon's A Concise Encyclopedia of Gastronomy:

Kiss-Me-Quick Pudding

Ingredients: The weight of 2 eggs in brown sugar and butter; 2 teaspoons of marmalade or jam; 6 oz. flour; 1 small teaspoon baking powder.

Method: Beat the sugar and butter to a cream; add the well-beaten eggs and beat to a cream. Add the jam, flour and baking powder. Steam in a basin for two hours.

Love and Tangle

Ingredients: 3 eggs, beaten; 3 tablespoons sugar; 3 tablespoons milk; flour, as needed.

Method: Mix the eggs and sugar and add enough flour and milk to make it thick enough to roll. Roll in thin strips about 6 inches long and 3 inches wide. Fold double by bringing one end up to the other. Beginning an inch or half-inch from the folded end, cut several slits down the open end. Drop in hot fat and fry until light brown. Drain and sprinkle with powdered sugar.