SUMMER IS the time for food that sparkles of freshness, for cold foods and picnic fare and for salads galore. These three sauces, two savory and one sweet, are all big and rich in flavor, quick and easy to prepare, and ideal for hot humid days when hours in the kitchen would seem unbearable even to the die-hard cook.

The first, a refreshingly piquant double mustard sauce, falls flat if concocted with ballpark mustard. Made with two great mustards, one coarsely grained from Meaux and a not-too-hot mustard from Dijon, it could easily become a summer favorite.

The second sauce, a tangy, deviled hollandaise, is a surprise for two reasons: One, hollandaises are never deviled; and two, the sauce is actually served cold--which means that you can make it ahead with no fear of the normally finicky behavior of a hollandaise.

The third sauce is a raspberry pure'e, with a sister strawberry sauce as a variation on the recipe. Made in a matter of seconds, this is a versatile accompaniment for summer desserts, from store-bought ice cream to fresh berries.

DOUBLE MUSTARD SAUCE (Makes about 2 1/2 cups)

Homemade mayonnaise for this sauce is certainly superior to store-bought. If making your own mayonnaise, use the minimum amount of vinegar or lemon juice, and do not salt or pepper until after the mustards have been added. 2 cups mayonnaise 1/3 cup coarsely grained mustard, such as one from Meaux 1/4 cup not-too-hot dijon-style mustard 1 small garlic clove Lemon juice or red wine vinegar Salt and freshly ground black pepper

Place the mayonnaise in a food processor fitted with the metal chopping blade. Add the two mustards and garlic and process until very well combined. Taste. Add a little lemon juice or vinegar, if desired, and season with salt and pepper.

* Use as a sauce with an assortment of fresh vegetables, crudite's

* Serve with hot or cold poached chicken

* Mix equal portions of the sauce with either sour cream or plain yogurt and use as a dressing for vegetable salads, cole slaw, salmon salad or chicken salad

* Serve with cold sliced roast beef, sliced veal or pork

* Serve as a sauce with hot or cold poached or grilled fish

* Use on sandwiches in place of mustard or ketchup

COLD DEVILED HOLLANDAISE (Makes about 2 cups)

Because of its butterfat content, hollandaise should be served at room temperature rather than cold. The addition of hollandaise makes some rather simple summer dishes formal and exciting without much effort. Covered tightly, this sauce can be made ahead and stored in the refrigerator for several days. Just bring to room temperature before serving. 3 sticks unsalted butter 3 egg yolks Salt and pepper to taste 4 or 5 small gherkins or cornichons 1 1/2 teaspoon Meaux mustard 1 tablespoon capers 1/2 small shallot Tops of 1/2 bunch scallions Small bunch fresh parsley Juice of 1/2 lemon

Place the butter in a saucepan and bring to a boil over medium heat. Don't worry, butter can be boiled without burning.

While the butter is heating, place the egg yolks, salt and pepper in a food processor fitted with the metal chopping blade and process for at least 90 seconds. Two or 3 minutes of processing is perfectly fine, also. When the butter reaches a full rolling boil, remove a small ladleful and very, very slowly dribble the boiling butter into the egg yolk, processing the whole time. After each ladleful is incorporated, return the butter to the burner to bring it back to a boil. Gradually add all the boiling butter, then turn off the processor.

Add the gherkins or cornichons, mustard, capers, shallot, scallion tops and parsley and process, turning on and off quickly, until these last few ingredients are coarsely chopped. Taste the sauce, add the lemon juice and season with salt and pepper. Process again until all ingredients are finely chopped. Be careful; do not pure'e by leaving the processor on too long. If you wish to adjust seasonings at this point, stir them into the sauce.

This can be made with beaters or in a blender like a normal hollandaise, then add the remaining ingredients, all very finely chopped.

* Use with blanched fresh asparagus or broccoli as a first course

* Serve with cold fish or roasted game

* Use anytime a recipe calls for sauce bearnaise

* Use as a dressing for cold sandwiches instead of butter, or in hot sandwiches such as grilled cheese or croque monsieur

* Serve as a dipping sauce for crudite's

* Drop a large dollop onto the top of saute'ed potatoes or sweet potatoes

* Serve with hot or cold slices of cooked Virginia ham

* Serve with roast leg of lamb studded with garlic and rubbed with rosemary

RASPBERRY SAUCE (Makes about 1 1/2 cups)

Although generally I am a purist about fresh ingredients, this sauce is fine with frozen berries if fresh aren't available. 10-ounce package frozen raspberries in syrup, or 1 pint fresh raspberries Juice of 1/2 to 1 lemon 3 tablespoons framboise (optional) 2 to 3 tablespoons sugar (if using fresh berries)

Defrost the berries and place in a blender or food processor with their juices or syrup. If using fresh berries, carefully pick over them to remove any moldy berries and bits of leaves. Add the lemon juice (I use the juice of a whole lemon, but this may make the sauce too tart for some tastes) and framboise, if using, and blend or process until smooth. If using fresh berries, sweeten to taste with 2 or 3 tablespoons sugar. Serve chilled or at room temperature.

Variation: Substitute fresh or frozen strawberries for the raspberries in the recipe. Use an orange-flavored liqueur, cognac or creme de cassis in place of the framboise.

* Use as a topping for ice creams, sorbets or sherbets

* Dress up slices of homemade pound cake, pineapple upside-down cake, or another cake of your choice

* Top fresh strawberries with it

* Pour it over poached pears or saute'ed apples

* Use to flavor milk shakes or smoothies

* Make great alcoholic summer drinks: Mix with freshly squeezed orange juice and a shot of dark rum, poured over ice cubes and served outdoors; mix with bourbon and ice and whirl in a blender for a frozen drink

* Melt an ounce of white chocolate per serving and fill the centers of pears that have been split in half lengthwise and cored. Pour sauce over them

* Arrange 3 or 4 fresh fruits in pieces decoratively around a plate, and serve with either raspberry or strawberry sauce passed separately

* Serve with pancakes or french toast instead of maple syrup or preserves

* Pour some of the sauce into the center of a fresh melon (such as canteloupe) or papaya before serving

* Serve with cold strawberry or raspberry souffle's