INVESTIGATIVE journalism suffers a setback each spring when the Gridiron Club gathers the newspapers' elite with the newsmakers who usually fill their pages, roasts them and toasts them and feasts in their company, then declares the whole shebang off the record. Thus last night's 97th annual musical satire and dining extravaganza by this 60-member club -- so exclusive that even spouses are not invited to the dinner -- was again reported second-hand, in warmed-over rehashes issued privately after the cocktails, sherry, white wine, red wine and champagne -- by "reliable sources."

But the hand that holds the whisk can also wield a scoop. Thus we have the first ever first-hand eyewitness report on the Gridiron Club's annual spring dinner for over 600 revelers at the Capital Hilton. Well, not actually on the dinner itself but, even better, the dinner behind the dinner.

It all began one dark and rainy night -- March 11, should history need to record it. Still, the stars shone on the midnight-blue rims of the Capital Hilton's china -- price unknown. Twenty good men and true (that's literary license -- the recently integrated Gridiron now includes women on its menu committee) sat in judgment of a preview menu, which replicated the dinner-to-be so perfectly that, as chef Walter Scheib put it, "We intentionally didn't do it any better" than it could be done for 600 people.

It was a historic occasion, the first time ever that the club was given a choice of menus to taste for its $85-a-person six-course dinner-and-show. Menu committee chairman Marianne Means (King Features Syndicate and Hearst) declared, "Democracy has come to the Gridiron Club," an assertion that was not immediately challenged. Thus two alternatives for each course were presented, each diner leaning over his neighbor to sample the alternate soup or fish course. And, this being serious business, each place was set with a score sheet. High-level highjinks are not taken lightly in this world; "I staked seven lives in this hotel on the success of this dinner," Hilton manager Fred Kleisner was heard to mutter.

First course, fruit. Papaya Fraisette, a papaya half stuffed with strawberries and papaya pulp macerated in passion fruit liqueur, won over a more routine presentation of sliced fruits. The group politely ignored a suggestion to have one for appetizer and the other for dessert, while Kleisner testified that papaya is a good starter for a dinner because it is not overly acid. That prompted one wag to ask, "Is there something you could serve that makes them tone deaf?" knowing that the music committee was out of hearing range.

Soup has continued to be a major unresolved issue for the Gridiron Club ever since the traditional terrapin soup was dropped from the menu in 1978 out of respect for endangered species. Truffles and foie gras, considered only expensive rather than endangered, appeared last year in a pastry-topped Soup Bocuse, but lost out this year to a cream of mussel soup garnished with a princely portion of saffron, arranged in precise narrow lines on a napkin, and doled out by a waiter with a tiny spoon, a procedure most recently popularized by the drug culture. CREAM OF MUSSEL AND SAFFRON SOUP (5 servings) 1 dozen mussels 1/2 cup white wine 2 to 3 cloves garlic Pinch oregano 1/2 medium potato, diced 1 leek, diced 1 medium onion, diced 1 stalk celery, diced 3 tablespoons butter 1 quart fish stock Pinch saffron 2 cups heavy cream Saffron strands for garnish

Wash mussels, then steam them in white wine, garlic and oregano. Pick mussels out of shell. Reserve liquor after straining through cheesecloth. Chop mussels very fine.

Lightly saute diced potato, leek, onion and celery in butter. Add fish stock, chopped mussels and mussel juice. Cook until vegetables are very tender. Pass through a food mill.

Put pureed liquid back in pot. Add saffron and heavy cream and boil to reduce by about 1/4. If necessary, adjust thickness and seasoning. Strain through fine strainer. Garnish with saffron strands.

Regionalism reared its head with the fish course, when the southerners -- a vocal minority -- voted for the Paupiette of Dover Sole with Scallop Mousse and Sorrel Sauce simply because it was "sole food." It apparently was less their wit than the deliciousness of the dish that carried the vote, for it was a delicate invention, garnished with impressively thick slices of truffle.

Being acutely attuned to the importance of public awareness, several of the judges worried about the heaviness of the meal, though it was pointed out that only one guest has been known to ever have fallen asleep during a Gridiron dinner.Still, a magnificent debate ensued over the filet mignon, whether it should be seven ounces or six ounces; the underlying issue of beef or no beef was simply not addressed. The club had already requested a lighter sauce this year -- bordelaise with bone marrow, but unthickened -- and no potatoes.And some of the radicals were ready to take stronger measures towards lightening the gastronomic load of the dinner. After protracted discussion and a tie vote between six ounces vs. seven ounces, a compromise of 6 1/2 ounces was reached. Ah, but policymakers may debate as they will; chef Scheib later insisted, "They're going to get seven ounces. I'm not going to be the one who drops the ball."

Vegetables are not ordinarily an arena for agreement, but there was little argument about the artichoke bottoms with leek gratinee, the julienne "confetti" of carrots, zucchini and the like, or the fresh asparagus.

The battle was reserved for dessert, fueled by the fact that there were three choices. Associated member Henry Gemmill couldn't muster support for his proposal to eliminate the fish course and have all three. But the dessert vote so endangered goodwill that it was considered prudent for everyone to clasp hands and sing "Auld Lang Syne" before the final vote. Individual baked alaskas evoked threats of civil war, with the southern contingent on the verge of secession, then throwing its votes as a bloc to the Coupe Framboise, an admittedly beauteous pink fluff in a tall flute glass, decorated with whipped cream, raspberries and a chocolate leaf. But the honor for eloquence went to the proponents of the Pear Iris, a marzipan-stuffed and chocolate-covered poached pear afloat on a custard sauce. Club president Ben Cole (Indianapolis Star) grew sonorous as he explained, "There are some things in the world that are just better than other things," and "When you combine pears and chocolate you have just almost reached the ultimate in taste." But when the vote went to the raspberry coupe, Cole relented in true newspaperman's fashion with, "They're not going to know what they don't get."

Only the wines seemed non-controversial, as the wine committee of B. J. Cutler (Scripps-Howard) -- the only diner to appear in black tie, which in Washington indicates that one must rush off to an embassy dinner -- and Andy Glass (Cox) explained that they were as drinkable as could be found within the "draconian budget."

Last night's dinner was, as usual, followed by champagne and petits fours with the gridiron logo, and if one wonders how the petits fours managed to be consumed, it should be remembered that in between courses the musical skits refreshed the palate and allowed time for digestive juices to work overtime. So the dinner lasted a good four or five hours, and those seven-ounce filets didn't appear before 10 p.m.

"It's very heavy dinner. There's a lot of food there," commented chef Scheib after the tasting, though it was a lighter menu than the club has had in the past. Essentially, the tasting was a choice of old-style vs. new-style, and in every case the committee unwittingly chose the new-style, lighter alternative. The fish course, for instance, was four ounces of sole instead of 10 ounces of lobster in the heavy, rich stew that was last year's fish course. Even so, for himself Scheib would consider the sole alone enough for dinner, with soup to start and fruit as dessert.

As only a chef could, Scheib thought it an easy dinner for such an occasion, considering that it was for 600 people and required eight minutes just to get the food up the elevator and into the dining room. Still, preparation of the canapes and painting of the aspic decorations on the trays began six days ahead, stocks were started three days ahead and the soups were set on the fire to reduce at 6 a.m. yesterday morning, since the process requires 10 hours.

The dinner used over two ounces of saffron -- at $36 an ounce -- the amount the hotel ordinarily uses in a month. Nearly four pounds of truffles were required, though Scheib admitted, "It's pointless to really use them," since canned truffles cannot be compared to fresh truffles, which are unavailable this time of year. Just the marrow for [TEXT ILLEGIBLE] requires 10 hours.

The dinner used over two ounces of saffron -- at $36 an ounce -- the amount the hotel ordinarily uses in a month. Nearly four pounds of truffles were required, though Scheib admitted, "It's pointless to really use them," since canned truffles cannot be compared to fresh truffles, which are unavailable this time of year. Just the marrow for the bordelaise sauce took nearly 150 pounds of bones. The dinner employed two-thirds of Scheib's kitchen brigade of 43 cooks.

All that, however, was just a beginning. Yesterday Scheib had to start at 5 a.m., knowing work wouldn't stop until midnight and, "The next day they are still here." Many of the guests from the Gridiron dinner have brunch at the hotel the next day, and this afternoon 1,100 people are expected at a reception after a repeat of the show for spouses and such. That means perhaps 5,000 finger sandwiches, not to mention the hotel's continuing responsibilities in the coffee shop, room service, public dining rooms, employe cafeteria and other banquets. And the Gridiron weekend includes 15 hospitality suites and exotic fruit trays for VIP rooms, plus the receptions before and after last night's dinner and the backstage dinner of what one of the cast called "fried chicken and dead sandwiches" for the Gridiron musical satire.

"The fact that there are so many VIPs, it's a tremendous strain on the hotel," explained Scheib, who at age 27, slim and bearded and taut with energy, looks as if he thrives on strain. "All you have to do is say Gridiron -- it's magic," he said; things the hotel can't ordinarily do simply happen for Gridiron. If repairing a range routinely requires two or three days, at Gridiron time it happens immediately.

As for Scheib, after such a fullblown banquet all he eats is fruit. "Believe me," he sums it up, "if you broil 600 steaks, you get tired of steak."

Here, for the cast who got only fried chicken, and those who were not among the chosen 600 this year, are chef Scheib's recipes for the dinner. And for those who disagree with Ben Cole that you're not going to know what you don't get, the outvoted Pear Iris has been included. The recipes have been reduced to serve five couples Gridiron-style -- which means the spouses have to stay home. PAUPIETTE OF DOVER SOLE WITH SCALLOP MOUSSE AND SORREL SAUCE (5 servings) 5 sole fillets (Chef Scheib uses Dover sole) 1/2 pound scallops 1/4 cup heavy cream 1 1/2 tablespoons brandy Salt and pepper 3/4 teaspoon glace de poisson (or substitute Knorr's Swiss Instant Fish Flavor) 1 egg yolk 1 cup fish stock 1/4 to 1/2 cup sorrel puree (sold in jars at specialty shops) White wine sauce; 1 1/2 tablespoons butter 1 1/2 teaspoons flour 1/2 cup fish stock 2 tablespoons white wine Salt, freshly ground black pepper 1/4 cup heavy cream blended with 1 egg yolk

Cut sole fillets in half lengthwise. Grind scallops finely; a food processor or blender can be used. Beat in cream, brandy, salt, pepper, glace de poisson and egg yolk.

Spread a layer of mousse on each sole filet and roll up, forming a paupiette. Place paupiettes in greased pan and add hot fish stock. Cover and poach lightly, about 20 minutes.

To make white wine sauce, melt the butter in a saucepan, stir in the flour, and cook gently over medium heat for two minutes without letting it brown. Mix in the fish stock and wine, and cook, stirring constantly, until it comes to a boil; simmer for two minutes. Season to taste with salt and freshly ground black pepper. Pour a little of the hot sauce into the egg yolk and cream mixture, and stir. Add this to the sauce in the pan and cook gently, over low heat, until slightly thickened, but do not allow the sauce to overheat or boil or the eggs will curdle.

Make sauce by adding sorrel puree to white wine sauce. Let reduce until as thick as desired, while stirring constantly.

Place 2 paupiettes on each plate. Pour sauce over and serve. ARTICHOKE BOTTOMS WITH LEEK GRATINEE (5 servings) 5 artichoke bottoms, canned or fresh 5 tablespoons butter 3 to 4 leeks, julienned Bechamel Sauce: 2 1/2 tablespoons butter 2 1/2 tablespoons flour 1 cup milk For filling: 2 egg yolks Salt and pepper to taste 1 tablespoon parmesan cheese

Saute artichoke bottoms in 3 tablespoons of the butter until light brown. Remove artichokes from pan and add remaining 2 tablespoons butter. Add leeks and saute until tender.

To prepare bechamel sauce, melt butter in a skillet and stir in flour. Cook for a minute or two, stirring. Whisk in milk and bring to a boil, continuing to stir until smooth.

Add bechamel sauce to leeks and allow to boil until reduced and thickened. Remove from heat and stir in egg yolks. Season to taste with salt and pepper. Let mixture cool.

Fill artichoke bottoms with mixture. Top with grated parmesan cheese. Finish in hot oven to brown. COUPE FRAMBOISE (5 servings) Sauce anglaise: 2 egg yolks 1/4 cup sugar $1% cup milk 1/4 teaspoon vanilla 1 pint raspberries 2 tablespoons sugar 1 1/2 teaspoons vanilla 3 tablespoons framboise liqueur 1/2 cup whipped cream, plus enough for garnish

To make sauce anglaise, combine egg yolks, sugar, milk and vanilla in the top of a double boiler and stir until custard thickens enough to coat a spoon, but do not let it boil.

Puree and strain raspberries. If using frozen raspberries, do not add sugar, but combine with just vanilla and framboise. If using fresh, add sugar, vanilla and framboise. Stir in sauce anglaise and gently fold in whipped cream.

Pour into fluted glasses and let set in refrigerator until firm. Garnish with whipped cream and raspberries. PEAR IRIS (5 servings) 5 pears 2 cups port wine 1 tablespoon vanilla 1 cinnamon stick 5 cloves 1/4 cup sugar 1/4 pound almond paste 1 1/2 tablespoons heavy cream 1 tablespoon Grand Marnier 1/2 pound imported chocolate 2 tablespoons clarified butter 5 almonds Sauce anglaise: 5 egg yolks 1/2 cup sugar 2 cups milk 1/2 teaspoon vanilla

Peel, core and poach pears in wine, vanilla, cinnamon, cloves and sugar. Let cool in mixture overnight.

Combine almond paste, cream and Grand Marnier until it reaches the consistency of mashed potatoes. Pipe mixture into pears.

Melt chocolate and combine with butter. Dip pears in chocolate. Garnish with almond and allow to cool.

To make sauce anglaise, combine egg yolks, sugar, milk and vanilla in the top of a double boiler and stir until custard thickens enough to coat a spoon, but do not let it boil.

Place about 6 tablespoons of sauce anglaise in each bowl and set pear on top.