The man who set the country's collective palate on fire with his trademark blackened redfish 4 1/2 years ago is heading a family effort to write a 175-recipe Cajun cookbook.

And Paul Prudhomme's older sister -- one of 12 family members assisting with the project -- has the formidable task of creating a recipe for stuffed redfish. "She's never seen a redfish," laughed Prudhomme, in Washington last month to discuss Cajun cuisine for the Smithsonian Institution.

But daunted she is not, according to Prudhomme, who readily admits his siblings probably think of themselves as better cooks than he. "I think in a lot of cases they might be," said the owner of New Orleans' K-Paul's restaurant. "They take the simplest of simple ingredients and make it taste good."

If simplicity is a hallmark of the 200-year-old Cajun culinary tradition, so too are variety and freshness. "Food should be raised with our hands," asserted the chef, an ardent supporter of the family farmer. Indeed, Prudhomme's standards were established practically in the cradle: as a child, his home was surrounded by red, white, and black pepper bushes, he said, and there were at least four varieties of cayenne alone. Prudhomme claimed he was "raised on valid canned goods" (those being his mother's home-grown products) and that the only snack food he knew growing up south of Opelousas was that which his family raised -- "peanuts, popcorn, and sugar cane for syrup."

Thus in his early travels around the country, Prudhomme was appalled at what was passed off as shrimp creole. "A dish with such a reputation had to taste better," he insisted. Indeed, when he went back to research the dish in Louisiana, he discovered that shrimp creole was a seasonal offering, prepared in summer when "the creole tomatoes were ripe and the shrimp season was on." ("The shrimp are full of fat in the head at their peak," he explained.)

Today, Prudhomme is naturally pleased with the revived interest in things Cajun -- but not necessarily with what everyone's doing to his signature dish, the ubiquitous blackened redfish. "There are so many awful versions, it's terrifying," lamented the chef. "It's not blackened -- it's burned."

The Prudhomme family cookbook remains in the testing stages, but for devotees of Cajun fare, today's Express Lane offers a Prudhomme favorite to enjoy before 1987, the anticipated publication date of the recipe collection. Following a trip through the express lane, all you'll need to have on hand are flour and butter to enjoy this smooth and pleasantly fiery dish.

Express Lane list: oysters, onions, celery, white pepper, cayenne, brie, whipping cream, champagne (optional) OYSTER AND BRIE SOUP (8 servings)

3 dozen small to medium oysters in their liquor, about 18 ounces

4 cups cold water

1 cup (2 sticks) unsalted butter

1/2 cup all-purpose flour

1 cup coarsely chopped onions

1/2 cup coarsely chopped celery

1/2 teaspoon white pepper

1/2 teaspoon cayenne

1 pound fresh brie cheese, cut in small wedges, with rind on

2 cups whipping cream

1/2 cup champagne (optional)

Combine oysters and water; stir and refrigerate at least 1 hour. When ready to use, strain and reserve the oysters and oyster water.

In a large skillet, melt the butter over low heat. Add the flour and beat with a metal whisk until smooth. Add the onions and celery; saute' about 3 minutes, stirring occasionally. Stir in the peppers and saute' about 2 minutes more. Set aside.

In a 4-quart saucepan, bring the oyster water to a boil. Stir in the saute'ed vegetable mixture until well mixed. Turn heat to high. Add cheese; cook until cheese starts to melt, about 2 minutes, stirring constantly (be careful not to let the cheese scorch). Lower heat to a simmer and continue cooking for about 4 minutes, stirring constantly. Remove from heat, strain soup, and return to pot. Turn heat to high and cook about 1 minute, stirring constantly. Stir in the cream; cook until close to a boil, about 2 minutes. Stir in champagne if desired. Turn off heat and add the oysters. Let pan sit about 3 minutes to plump the oysters. Serve immediately.

From "Chef Paul Prudhomme's Louisiana Kitchen" (Morrow, 1984)