ASK DORIS Matsui what has been the most difficult adjustment for her as a hostess in her first term here as a congressional wife and she replies, "the unpredictability of the weather."

Back home in California (Sacramento), she explains, "the outdoors was always part of our entertainment plans.We did a lot of large buffets with barbecued meats and even in February it was nice enough to be outside. We would put space heaters inthe patio and move outside after brunch."

When she came East last fall to join her husband Robert, a Democrat who sits on the Interstate and Foreign Commerce and Government Operations committees, Doris Matsui cast a worried eye on the relatively small yard of the Kenwood home where they were to live. "I was worried about where I would put people, but after a winter here and what I've heard about the heat of summer, I think it wouldn't matter. I would end up inside the house with my guests just looking at the yard.

"I realized I would have to do smaller parties. But then I learned that with all the receptions and large parties here, people appreciate an intimate dinner or a small buffet. At a large party, you tend to skim past people. It's not as much fun as sitting at a table and really enjoying your company. In Washington there are people with so many different backgrounds and interests that it's fun to compose a guest list. I've had a couple of disasters, but you learn."

Learning appears to be a second instinct. A graceful and lively woman with a distinctly upbeat disposition, Doris Matsui was born at a relocation camp in Arizona, obtained a degree fro m the University of California at Berkley and worked as a systems analyst-before marrying in 1966. She makes her own clothes and cares for the numerous plants in her home with the skill of a professional gardener.

She quickly adjusted to one aspect of Washington culture shock -- entertaining during the week when everyone is in town instead of on the weekends -- but is still suffering from another. It's difficult, she said, to shop for the twice-a-month dinners the Matsui's give when time allows because the supply and quality of fresh produce is so unpredictable. "I couldn't believe how expensive artichokes are here," she said. "At home we used to cook up a batch and use them as snacks. And Avocados. I haven't found a really good avocado since I've been here. So it takes longer to get things organized. I go to the market with a list, end up with something else and have to revise my menu."

Thanks to her husband's frequent trips back to his district, she receives care packages from time to time. In addition to avocados and oranges, she has welcomed the arrival of fresh wonton skins and tortillas, as well as pineapples, grapefruit and sugar snap peas. It's not all negative, though. She is very enthusiastic about the fish, so enthusiastic in fact that the Matsuis, both Japanese-Americans, have begun eating sashimi (raw fish) for the first time.

Doris Matsui is well-known for her cooking skills, but she has never taken a lesson. "My mother was a great cook. We had a country kitchen with a big round table and everybody got into the act. My sisters and I all like to cook and sew. It was part of our lives growing up. My mother always experimented with recipes and so do I. Sometimes Bob gets upset when I serve something with a new twist. He'll say, 'I really liked the way you did it last time.'

"But as much as I like to cook, I don't want to be nervous about how a dish is going to turn out for company and I'm not going to spend the evening cooking in the kitchen. If you're not around and can't talk to your guests, what's the use of having them over?"

Her pattern is to do sit-down dinners for six or eight without help. For a buffet with 18 or 20 guests, she will prepare the food and hire someone to serve. "People are inclinded to be more formal here," she said, "so I try to put in some California informality. Not gingham tableclothes, but I will cut down on the courses. I may use a salad as an appetizer instead of serving it after the main course. You won't get a last-minute souffle from me. It's not y style.

"I think a cook should pick her specialities and spotlight them. Don't try a dish you've never done before on company. Even if it works, you're going to want to make adjustments. Try it on your family first. Also, don't be afraid to serve something simple. If I do stuffed trout as a first course, I will do something simple, maybe barbecued beef, for a main course and then serve a smashing dessert. Women tend to worry that they have to serve fancy food, but it can work the other way, too. If you are too gourmet, your guests think 'how can I do this at my house.' It will inhibit them.

First or main-course salads, "almost anything" wrapped in wonton skins, frozen and reheated as appetizers, steamed fish with an oriental sauce and food from the barbecue cooker are often on Doris Matsui's menus. So, understandably, are California wines. She is eclectic in her taste, serving an Italian or French dish, but rarely an entire ethnic menu. "Not even Japanese," she said. "There is too much up and down in doing Japanese cooking." For dessert often she will offer guests a choice: fresh fruit or a calorie-rich cake or mousse. "That way people who are dieting don't have to pass it up. But often they take both."

As is often the case with people in public life, the Matsuis like to relax when alone or with friends. When Bob Matsui works late on Capitol Hill, Doris often will stir-fry something for their 10-year-old son, Brian, then make a second batch later for her husband. "I do stews that can be reheated, or something quick like oriental-style steak or sashimi. I'll only cook a roast when I know Bob is coming home at a certain hour. Then I'll use the leftover meat for sandwiches. Sometimes he'll bring someone or we'll ask another couple over. Then we eat in the kitchen."

The kitchen itself represents another contrast with California. "Kitchens are so small here, so tucked away" she said. "It's as though people were embarrassed about them. In Sacramento, our family room adjoined the kitchen and we did our informal dining there. There was a separation but no wall, so I could hide the mess in the kitchen and still be part of everything. Here everyone gravitates toward the kitchen, but there is nowhere to put them.

She paused for a moment. "I'll have to improve it somehow." ARTICHOKE CHICKEN-RICE SALAD (6 to 8 servings) 1 package chicken Rice-a-Roni 2 green onions, chopped 1 green pepper, chopped 1 small can sliced black olives 2 jars (6 ounces each) marinated artichoke hearts, drained (save marinade) 1/2 teaspoon curry 1/3 cup mayonnaise

Cook rice according to package directions. Mix marinade from artichokes with mayonnaise and curry. Add to cooked rice. Combine remaining ingredients with rice and refrigerate. Keeps for several days.

Variations: Add 1 cup cooked shrimp or crab or 1 cup chopped or cubed chicken. ASPARAGUS SALAD (8 servings) 2 pounds fresh asparagus, cut into even lengths 1/2 cup olive oil 2 tablespoons wine vinegar 1/4 teaspoon salt 1/8 teaspoon pepper 2 teaspoons chopped parsley 2 cooked egg yolks, sieved 1 tablespoon capers

Cook asparagus. Cool. Put into shallow dish. Combine oil, vinegar, salt, pepper and parsley and pour over asparagus. Chill overnight. To serve, garnish with egg yolks and capers. TASTY SPARERIBS (4 servings) 4 pounds spareribs in slabs Black pepper and garlic salt 1/3 cup sugar 1/3 cup brown sugar 1/3 cup soy sauce 1/3 cup hoisin sauce 1 clove garlic, crushed 2 tablespoons white wine

Place spareribs in pan and sprinkle with pepper and garlic salt. Place foil over pan and seal tightly. Place in a 350-degree oven and cook for 1 hour.

Meanwhile, prepare marinade by combining sugars, soy sauce, hoisin, garlic and wine. Remove spareribs from oven and cut into individual ribs. Place in marinade and marinate in refrigerator for at least 3 hours.

When ready to serve brown under broiler or place over hot coals until browned.

Note: This marinade can also be used for duck: Increase the soy sauce to 1/2 cup. Place the duck and marinade in a plastic bag in the refrigerator for at least 24 hours, turning occassionally. The duck can then be cooked outdoors in a covered barbecue for about 50 to 75 minutes. SURPRISE MERINGUE COOKIES (Makes about 3 dozen) 2 egg whites at room temperature 1 teaspoon vanilla extract Pinch of salt 1/2 cup sugar 1 cup mini chocolate chips 1 cup chopped pecans

Preheat oven to 300 degrees. Beat eggs whites until they hold a shape, then add vanilla extract and salt. Continue beating while gradually adding sugar until mixture is thick and glossy. Fold in chocolate chips and pecans. Drop by spoonsfuls onto foil-lined cookie sheets. Bake for 30 minutes. -- From "San Francisco a la Carte Cookbook," by the Junior League of San Francisco STUFFED BAKED TROUT IN CREAM (4 servings) 4 fresh trout fillets or any other white meat fish (each about 10 inches long) 1/4 teaspoon salt 1/8 teaspoon white pepper 2 tablespoons lemon juice 3 tablespoons butter 1 cup cooked rice 1 small onion, sliced 4 tablespoons vermouth 6 tablespoons heavy cream 1 teaspoon dried tarragon Fresh soft breadcrumbs 1/4 cup melted butter 1/2 cup chopped parsley

Wash and dry trout thoroughly. Cut each fillet in half cross-wise. Sprinkle with salt, pepper and lemon juice. Melt 3 tablespoons butter in a heavy skillet and saute fillets slightly. Remove and place a half fillet in each of 4 au gratin dishes.

In same in skillet, saute' onions until lightly browned and add cooked rice.

Stir and cook until heated through and season with salt and pepper to your taste.

Put rice/onion mixture over each half fillet in the au gratin dishes. Place the remaining half fillet on top of the stuffing mixture. In each dish pour in 1 tablespoon vermouth and 1 1/2 tablespoons cream. Sprinkle each with 1/4 teaspoon tarragon. Cover each dish with foil and bake in a preheated 350-degree oven for 20 to 25 minutes.

Remove dishes from oven and cover with bread crumbs. Spoon melted butter over each fish dish and place under broiler until lightly browned. Garnish with chopped parsley and serve at once. LEMON TORTE 1/2 bag Pepperidge Farm lemon crunch cookies, crushed 3 tablespoons melted butter 4 eggs, separated 1 cup sugar 1 1/2 cups whipping cream 1 1/2 tablespoons grated lemon rind 1/2 cup lemon juice 1 carton frozen raspberries, thawed

Mix together cookie crumbs and and melted butter and press into bottom of springform pan.

Beat egg whites and add sugar gradually. Beat egg yolks and add lemon juice and rind. Set aside. Beat cream. Fold all mixtures together. Pour into springform pan and place in freezer until frozen. Let thaw for 10 minutes before serving. Place raspberries in blender until liquified. Pass as sauce. FOOD PROCESSOR CHOCOLATE MOUSSE (4 servings) 1/4 cup sugar 1/3 cup water 1 package (6 ounces) semi-sweet chocolate pieces 3 tablespoons dark rum 3 egg yolks 1 1/2 cups heavy cream, whipped

Combine sugar and water in a small saucepan. Boil for 3 minutes. Use metal blade of food processor and add cream to beaker. Process uninterrupted for 1 minute.

Transfer to another bowl. Add chocolate to beaker and process for 20 seconds off and on. Continue processing and gradually pour in hot syrup; rum and egg yolks. Using spatula carefully fold in chocolate mixture and whipped cream. Pour into demitasse cups or pots de creme and refrigerate. CHEESECAKE ELEGANT Crust: 1 cup graham cracker crumbs 1/4 cup confectioners' sugar 1 teaspoon allspice 1/4 cup melted butter Filling: 24 ounces cream cheese 1 cup sugar 3 tablespoons light rum or 2 teaspoons vanilla 2 eggs beaten lightly

Combine crust ingredients and press into the bottom of a springform pan.

Stir cheese til creamy -- add eggs, sugar and flavoring. Beat until smooth. Pour into prepared crust. Bake 25 minutes at 350 degrees, then top with 2 cups of sour cream mixed with 4 tablespoons sugar and 1 tablespoon sherry or vanilla. Return to oven and bake 10 minutes more. When cool, top with 1 can cherry pie filling or blueberry pie filling.