My father liked to eat native a long time ago. He was unusual in the United States in his time. He was a bon vivant . I'm convinced his feeling was instinctive for the basic things that are good."

Ernest Hemingway's eldest son, Jack, is relaxing on the terrace of his ranch-style home overlooking the Sawtooth Mountains, reminiscing about his father and the family's four-generation romance with food. He is sipping a glass of wine after a hard tennis game while his daughter, Mariel, the young star of "Manhattan," is performing on the trampoline. "Papa" Hemingway spent the last years of his life hunting in the same mountains, fishing in the nearby streams.

The Hemingways first started coming to Ketchum, the little town next to Sun Valley, in 1940. Jack, 55, and his wife, Puck, moved here in 1968. Income from Ernest Hemingway's estate has made it possible for his son to pursue a life of fly fishing, hunting, tennis and writing. Recently he added cooking to his hobbies.

"Food has always been a thing in our family. There's only one problem," he says, having moved inside to prepare some truite au bleu . "I can do any one thing quite well, but I can't do two things.I can't make them all come out at the same time."

While Jack poaches the fish in the eight-food-square kitchen, the two younger Hemingway Daughters - Margaux and Mariel, home between movie and modeling jobs - are baking chicken and steaming vegetables. Everyone is talking at once.

Puck Hemingway is steaming nettles. She knows how to make the various elements of a dinner come together. She is a former Cordon Bleu student and the matron of honor at her wedding was Julia Child. "Julia wasn't doing any cooking at all then," says Puck.

The Hemingways discovered the delicacy of pureed nettles last summer. Although his wife disapproves, Jack picks the stinging plants without gloves. "My fingers get swollen for about a day, then it goes away."

The week before they had been morel hunting. "You gotta be in the right woods at the right time. A warm day after a wet day. But watch out for certain kinds of morels with wine," Jack Hemingway cautions. "They're like a hallucenogenic."

Puck Hemingway didn't think she would like cooking, but after she married Jack in Paris in 1949, she thought she'd better take it up. "Jack has always loved to eat, I guess because he grew up in France. My mother was a very good cook, too."

Jack's fishing trips are down to about 100 days a year, though there have been 200-day years. "Steelhead and Atlantic salmon, the 'prince of fish' are his favorite, but Hemingway, who is Idaho's fish and game commissioner, likes any sport fishing.

He is a strong conservationist. As commissioner he was able to convince state officials to stop stocking certain waters with hatchery trout. "Hatchery trout are like New Yorkers who live crowded together. Eventually the hatchery trout shove the wild trout out. They aren't used to congregating together and eventually they go crazy and disappear. Then the hatchery trout, which aren't used to the wild waters, die over the winter. Now they keep certain places wild and put the hatchery fish in reservoirs," Jack explains.

Much as he likes both fishing and hunting, Jack doesn't like to hunt too many birds in a year, though he says he's willing to "eat as many as all my friends can kill." Not rare, however, which is how many bird hunters like to serve goose. "I've eaten all these things those guys rave about," Jack says, "but I notice they drink five martinis beforehand."

This year's greatest eating pleasure has been neither fish nor fowl. It was moose. Jack says he "shot the only moose of a lifetime" because only one per hunter is allowed by state law. "It's one of the finest meats you can ever eat. It's not fat but very rich." Jack, became interested in pasta making by Waverley Root's "Food of Italy" - "I read the recipes and drool" - made moose ravioli from stratch with some of the meat.

Jack's just back from France, where he had escorted Mariel to the Cannes Film Festival showing of "Manhattan," and he wants to make his next European trip a gustatory and fishing expedition through Italy.

Getting good food in Ketchum is something of a problem. The growing season is very short. The markets are "hideously expensive," Puck says, so she does a lot of shopping when she goes to Boise, a three-hour drive away. During the summer, fresh fish is trucked down from Washington state and some young people run an openair market once a week.

But even with two out of three daughters home, Puck can not indulge in food pleasure. "Everyone's on a diet," she says. Jack is trying to take off five pounds he put on in France and Los Angeles. Margaux is following one of the newest fad diets and Mariel is a vegetarian. Ernest Hemingway was always watching his weight, too, Puck recalls. "I remember down in Cuba in their house he'd write his weight on the wall. The wall was filled with his weights."

But whenever the eldest daughter, Joan, called Muffet, is home she and her mother spend a lot of time in the kitchen. Muffet is the co-author of a charming cookbook, "Picnic Gourmet," which contains many of her mother's recipes, including a favorite for Chocolate Walnut Torte that she "never gives out."

Puck complains that "she took all my recipes." She was particularly surprised to find the torte in the book, hidden away in a chapter on birthday picnics. It was served for Muffet's birthday this year along with soup, made from watercress picked from the banks of the river, grilled butterflied lamb and fennel said.

As well as fishing and writing articles about it for magazines, playing tennis and cooking, Jack Hemingway is writing a novel - a World War II love adventure. "I wanted to write a book about Hemingway's Paris, but a professor beat me to it. I suddenly realized other people were making a living off all the things that have to do with my family background so I've got one good story to tell and I'm telling it."

Jack Hemingway admits that his name is an asset, but he says, perhaps only partly in jest, "I spent my whole life being the son of a famous person. Now I'm the father of a famous person. When the hell am I gonna be me?"

These are some of the recipes appearing in "Picnic Gourmet"

PAELLA

(6 servings) 1 stewing chicken, cut up and cooked 2 chopped onions 2 cloves garlic, minced 4 sliced Spanish sausages (chorizo) 2 tablespoons olive oil 4 cups reserved chicken broth 2 cups quick brown rice 1 can (16 or 17 ounce) tomatoes 1 package frozen peas 1 teaspoon salt 1/2 teaspoon oregano 1/2 teaspoon tarragon 1/8 teaspoon saffron 1 cup cooked shrimp 12 whole little neck clams, scrubbed 1 package frozen artichoke hearts, cooked pimiento strips for garnish

Saute onion, garlic and sausage in olive oil for 5 minutes. Add rice, chicken broth, tomatoes, peas, salt, oregano, tarragon and saffron. Cover and simmer 15 minutes. Add cooked shrimp. Meanwhile steam the clams a few minutes until their shells have opened. Arrange rice mixture in large, ovenproof serving dish. Place chicken and clams on top and bake at 375 degrees for 15 minutes. Garnish with pimento strips and artichoke hearts.

POACHED STEELHEAD OR SALMON

This recipe is equally appropriate for any similar 4 or 5 pound whole fish.

(6 to 8 servings) 4 to 5 pounds whole steelhead or salmon 1/4 cup chopped shallots 1 stalk celery with leaves, cut up 1 carrot, cut up 4 sprigs parsley 1 tablespoon salt 4 cups water 2 1/2 cups white wine 2 lemons, cut in wedges Mornay Sauce (see recipe below)

Combine shallots, celery, carrot, parsley, salt and water. Bring to boil, reduce heat and simmer uncovered 20 minutes. Strain through double thickness of cheesecloth and discard vegetables. Pour this court bouillon into a fish poacher. Add wine. Wash fish inside and out, pat dry with paper towel. Place fish on rack and put in pan. (If using roaster instead of poacher, and do not have a rack, wrap fish in cheesecloth, leaving long ends to help lift it out.)

If fish is not at least half covered by bouillon, add up to 1 cup extra of water. Bring liquid just to boil; cover and poach fish over very low heat for 45 minutes or just until fish flakes easily with fork. Carefully lift rack with fish on it from pan. Drain well. Strain bouillon and save for sauce.

MORNAY SAUCE Fish poaching liquid 3 tablespoons butter 1 cup milk 4 tablespoons heavy cream Few drops lemon juice 1/2 cup grated Swiss cheese

Rapidly boil down fish poaching liquid until it has been reduced to about 1 cup. Melt butter, blend in flour and cook slowly for 2 minutes. Remove from; slowly add fish poaching liquid, blending with wire whisk. Bring to a simmer, stirring. Add milk and continue cooking until thick enough to coat spoon. Add heavy cream. Season with salt, pepper and lemon juice. Remove from heat and stir in Swiss cheese. Serve over poached fish.

CREPES FRANGIPANE

(Makes 12 crepes) 4 heaping tablespoons flour 1 egg 1 egg yolk 1 tablespoon butter or margarine, melted Dash salt 1 tablespoon sugar 1 cup milk Cream Filling (see recipe below)

Melted butter Grated unsweetened chocolate Confectioners' sugar Whipped cream

Whisk until smooth the first seven ingredients, using 3 tablespoons of the milk. Then add enough of the remaining milk to make batter of thin consistency. Refrigerate for 3 or 4 hours. Remove and add enough of remaining milk to reduce again to thin consistency, between light and heavy cream. Heat a 6- or 7-inch crepe pan; when very hot wipe out with with piece of slightly buttered wax paper. Return to lowered heat. Cover bottom of pan with very thin layer of batter. Pour off any excess. Cook until golden on one side. Stack them as they cook. Using the same piece of wax paper, rebuttering occasionally, rub the bottom of the pan between each crepe.

Crepes may be frozen, stacked, if desird.

Spread about 2 tablespoons Almond Crean Filling on unbrowned side of each crepe; roll up and place folded side down in buttered baking dish (9 - by - 13 approximately). Brush crepes with melted butter and bake at 350 degrees 20 to 25 minutes or until hot. Sprinkle with grated unsweetened chocolate and sift confectioner's sugar over. Serve warm with whipped cream.

ALMOND CREAM FILLING 1 cup sugar 1/4 cup flour 1 cup milk 2 eggs 2 egg yolks 3 tablespoons butter or margarine 2 teaspoons vanilla 1/2 teaspoon almond extract 1/2 cup ground toasted blanched almonds

Mix sugar and flour. Add milk; cook and stir until thick. Continue cooking and stirring 1 or 2 minutes longer. Beat eggs and yolks slightly; stir some of hot mixture into eggs and return to stove. Bring just to boil and remove from heat. Stir in remaining ingredients. Cool to room temperature or refrigerate if desired until ready to use

RAIL OR WOODCOCK EN CASSEROLE

The Hemingways hunt woodcock, or snipe. They suggest that rail, more often hunted on the East Coast, be cooked the same way. 4 rail or woodcock 4 tablespoons flour 8 tablespoons butter 2 green onions, finely chopped 1 carrot, finely chopped 1/4 teaspoon basil 2 pinches tarragon 1 medium-sized apple, peeled and diced 1/2 cup chicken stock or broth 1 cup dry white wine 1/2 bay leaf 1 cup sour cream Salt and freshly ground pepper

Rub the birds inside and out with salt and pepper and dust them with flour. In large saucepan melt butter; add green onions, carrot, basil and tarragon. Stir and cook 5 minutes. Add birds and saute until lightly browned. Place birds in casserole.

To saucepan add apple, stock, wine and bay leaf. Simmer 30 minutes; strain and pour over birds. Add sour cream; cover casserole and cook at 325 degrees for 45 minutes. Remove cover and cook an additional 10 minutes. Season to taste with salt and pepper.

CHOCOLATE WALNUT TORTE

This is a special birthday cake made from an old family recipe. Though not easy to take on a hike, it can be served out doors if protected by a cake cover and taken in a car to the picnic site. You can take the Chocolate Whip Topping in a separate container if you prefer. In this case, wrap the torte in plastic wrap and frost it at picnic, keeping it cool in an ice pack or cooler until it is time to frost the cake. 1/2 cup shortening 1/2 cup sugar 1/2 teaspoon vanilla extract 4 egg yolks 1 cup all-purpose flour Dash of salt 1 teaspoon baking powder 1/2 cup milk Walnut Meringue (recipe below)

Preheat oven to 300 degrees and grease and flour two 8-inch round cake pans. Cream shortening and sugar. Add vanilla and egg yolks, one at a time, beating after each addition. Sift flour with salt and baking powder, and add alternately with milk. Pour into pans. Now spread the unbaked cakes with Walnut Meringue: 4 egg whites 1/8 teaspoon cream of tartar 1 cup sugar 3/4 cup finely chopped walnuts

Put the egg whites and the cream of tartar in the large bowl of an electric mixer, and beat at high speed, adding the sugar 2 tablespoons at a time. When stiff peaks form, fold in the walnuts. After spreading the cakes with the meringue, bake for 1 hour. Cool layers. Frost with Chocolate Whip Topping: 1/3 cup cocoa 3/4 cup sugar 1 1/2 cups heavy cream Several walnut halves

Add cocoa and sugar to heavy cream, stirring well. Let this mixture stand 1 hour, then with an electric mixer beat at high speed until stiff. Garnish frosted torte with walnuts.

COLD CREAM OF WATERCRESS SOUP

(Makes 1 1/2 to 2 quarts) 1 1/2 tablespoons butter 1/4 cup minced onion (1/2 medium onion) 5 cups watercress, well washed and patted dry 1 1/2 tablespoons flour 3 cups boiling chicken stock 1/2 teaspoon salt 1 egg yolk 1/4 cup cream or 1/2 cup light cream or milk

Melt the butter in a large (2 1/2 to 4 quart) heavy-bottomed pot. Over low heat saute the onions in the butter for about 10 minutes, or until just transparent. Turn up the heat a bit and stir in the watercress, which will cook and wilt almost like spinach, so the whole 5 cups can be added to the pan. After 5 minutes turn the heat up to medium, add the flour and stir another 5 minutes. Next add the hot chicken stock and stir. Let the soup cool. Now puree the mixture in either a food processor or blender, then again through a food mill or fine sieve. (This step is to break up the stringy consistency of the watercress. Putting it through a blender is not enough. You can eliminate the blender step but not the food-mill process.)

Return to the pot and add the seasoning, tasting if more salt is required. Often a soup like this will need more salt to bring out the flavors after it is finally chilled, as food tastes more bland when cold. Now mix the egg yolk and light cream together in a bowl. (For a thicker version, heavy cream may be used. Use milk for a lighter refreshing soup.) Add some of the hot pureed liquid, spoonful by spoonful, to the bowl, until there is about a cup of soup mixed well with the cream and yolk mixture. Add this to the rest of the liquid in the pot. Simmer 10 minutes, but don't let the soup come to a boil. Set aside to cool and refrigerate for 3 hours before puring into a thermos. Decorate each serving with watercress leaves and their flowers. CAPTION: Picture; Mariel, Puck Margaux and Jack Hemingway at home in Ketchum, Idaho, photos by Susan Synder Cooke for The Washington Post. Ernest Hemingway, inset.; Pictures 2 and 3, no caption; Jack and Puck Hemingway, by Susan Synder Cook for The Washington Post