APRIL SHOWERS bring May flowers -- and soft-shell crabs.Much to to delight of those who love eating them, they hang around in the Chesapeake Bay through mid-September. Millions of them.

Soft-shell crabs are one of the gastronomic wonders of the world. Ducks have their feathers and deer their antlers; with a soft-shell crab you can pretty much eat it all. No discarding shells or picking through cartilage; the soft-shell crab is the Atlantic Blue Crab in a convenient -- if temporary -- waste-free package.

When a crab moults, which a female does 18 to 20 times in her lifetime and a male about 23 times, the hard outer skeleton disintegrates and the crab swims free. This is when the crab grows, sometimes by one-third its size. Unfortunately, a new shell begins to form within 24 hours, and two days later the shell is rock-hard.

The key to having perfectly delicious soft-shell crabs is buying them when they are tiny and feel velvety smooth. The smaller the soft-shell, the juicier and sweeter it will be. Bigger is better only because you get more.

They can be bought in three sizes: mediums, which ae smallest, measure 3 inches across the back and cost around $15 a dozen; prime, or midsize, are 4 inches and cost around $17 a dozen; jumbos are 6 inches and cost around $19 dozen. Plan to serve your guests three medium, two prime or two jumbos each. They are available in many local fish markets, but be sure to call ahead; availability depends on the day's catch.

Cleaning soft-shells is a s imle task. Lay the live crab belly-up. With a knife, cut the h ead section out behind the eyes, then slip your knife inside and pull out the clear sac, which is the stomach. Run a knife under the apron (the bell-shaped portion of the belly) and cut it away. Flip the crab over, lift each side of the loose, soft shell and cut away the lungs ("devil's fingers" to fans of hard-shell crabs). Wash in cold water, and they are pan-ready. If this doesn't sound like your kind of food preparation, have the market clean the for your. In any case, be sure to eat them within 24 hours of buying them.

You can sauti, deep-fry, broil or grill. They are juiciest sauteed, crunchiest deep-fried, and crusty and moist broiled or grilled. The soft-shell crab sandwich is usually a sauteed or deep-fried crab, served on a fresh, soft bun with a little tartar sauce.

To saute heat 2 tablespoons of butter to a bubbling golden brown in a heavy frying pan. Salt, pepper and sprinkle the crab with fresh lemon juice. Cook for 2 minutes on each side. Serve immediately with lemon wedges on the side.

To deep-fry, coat the crab with egg, then dredge in flour seasoned with salt and pepper and, if you want, some tarrgon or cayenne. Let the crab sit for 20 to 30 minutes before cooking to set the cooking. In a heavy pan, heat enough oil to cover the crabs. Oil is ready when a tiny piece of bread sizzles to a quick crisp. Lower crabs in the hot oil and deep-fry until golden brown; how long depends on the size of the crab. Do not overcook; a dried-out soft-shell crab is quite disappointing. When done, remove with a slotted spoon or tongs and place on paper towels to drain. Serve hot.

Two other advantages to eating crabs: They are low in calories (93 per 3 1/2-ounce serving) and carbohydrates, and high in protein, calcium, phosphorous and vitamin A. And they go well with almot anything. I like to keep things simple and use whatever is fresh on the market -- tomatoes and basil, fresh green beans or yellow squash, boiled new potatoes.

Be self-indulgent and treat yourself to all of the following recipes. There are enough to keep you busy through the end of the season and leave you thinking about April showers long before the first winter snow. SOFT-SHELL CRABS IN BLACK BEAN SAUCE (2 servings) 4 medium soft-shell crabs, cleaned 4 tablespoons oil for frying 2 cloves garlic, minced 2 teaspoons minced ginger 2 tablespoons fermented black beans, rinses and chopped (available in Chinese grocery) 2 cloves garlic, mashed 2 tablespoons soy sauce 2 tablespoon rice vinegar 1 tablespoon rice wine 1 cup chicken stock 1 tablespoon cornstarch 2 eggs, beaten 1/2 cup minced green onion, for garnish

Cut each crab in quarters. Heat the oil in a wok and toss in the minced garlic and ginger. When they become fragrant, add the pieces of crab and fry until bright red. Remove the crab and add the black beans, mashed garlic, soy, vinegar and wine. Cook 1 minute. Add the chicken stock and brong to a boil. Return crab and cover the pan. Cook for 3 minutes. Mix the cornstarch with a little water and add to the wok. Cook until thick. Stir in the beaten eggs. The sauce will turn white. Pour onto a platter and sprinkle with green onion. T. GREGORY'S SAUTEED SOFT-SHELL CRABS (2 servings) 4 jumbo soft-shell crabs, cleaned Flour for dredging Vegetable oil for frying 6 pieces white toast, for serving Sauce: 8 to 10 tablespoons sweet butter 1 teaspoon each minced parsley, tarragon, basil, chives 6 to 8 tablespoons white wine Juice of 1 lemon Salt and freshly ground white pepper

Lightly dredge soft-shell crabs in flour. Heat oil in 2 frying pans and saute 2 to 3 minutes on each side. Remove to warm platter.Discard oil.

To make sayce, melt butter with herbs in frying pan. Add wine, lemon juice, salt and freshly ground white pepper to taste. Cook until reduced by half. To serve, place crabs on 1 1/2 pieces of toast. Top with sauce. SOFT-SHELL CRABS MENUNIERE (2 servings) 4 jumbo soft-shell crabs, cleaned Salt, pepper and lemon juice, to taste Dijon mustard Flour, for dredging 6 teaspoons butter 4 teaspoons minced parsley Tartar sauce, as garnish

Season crabs with salt, pepper and lemon juice. Brush bellies with dijon mustard. Dip both sides in flour. In large frying pan heat 2 teaspoons butter. Saute crabs on both sides, about 2 minutes on each side. Sprinkle each with 1 teaspoon parsley. In a separate pan heat 4 teaspoons butter in and cook until a rich nutty brown. Pour 1 teaspoon butter over each crab. Serve with tartar sauce on side. SOFT-SHELL CRABS BEURRE NOISETTE (2 servings) 4 jumbo or 6 medium soft-shell crabs, cleaned Cold milk 2 cups flour 1 teaspoon salt 1/2 teaspoon freshly ground black pepper 1/4 teaspoon cayenne Vegetable oil for deep frying Beurre Noisette: 1 1/2 sticks butter 1 cup slivered, blanched almonds (optional) 2 teaspoons fresh lemon juice 1/2 teaspoon freshly ground white pepper

Dip crabs in cold milk then flour mixed with salt, pepper and cayenne. Heat 1/8 inch oil in bottom of frying pan and saute 3 to 5 minutes on each side. Remove from pan and cover to keep warm.

To make sauce, melt butter over medium heat in a 2- to 3-quart saucepan. Add optional slivered almonds. Cook just until the butter begins to brown, then remove the pan from the heat. With a slotted spoon remove almonds from butter and set aside until serving. Add the lemon juice and pepper and mix with a wooden spoon. The sauce will foam up. When the foaming subsides, return the pan to the heat and cook for 1 to 2 minutes longer, or until the sauce turns a rich hazelnut brown. Remove from the heat. To serve, place sauteed crabs on heated plates. Sprinkle with almonds. Stir the sauce thoroughly and spoon about 3 tablespoons over each portion. Adapted from "The Pleasures of Seafood," by Rima and Richard Collin SOFT-SHELL CRABS CHARCOAL GRILLED IN SOY SAUCE (2 servings) 1/4 cup soy sauce 1 1/2 cups white wine 1/3 cup olive oil 2 tablespoons Szechuan "hot oil" or 5 to 6 drops hot pepper sauce 2 cloves fresh garlic, chopped 4 jumbo crabs, cleaned

In shallow baking dish mix soy, wine, olive oil, hot oil and garlic. Add soft crabs and cover. Marinate for 1 1/2 hours.

Wait for the coals to stop flaming in grill, place crabs on rack. Turn a few times, baste frequently and cook until red, firm and slightly crisp. To decrease cooking time, cover grill with a large lid to help circulate heat evenly. Crabs are cooked when red, firm and slightly crisp. BROILED SOFT-SHELL CRABS (6 servings) 12 jumbo soft-shelled crabs, cleaned Flour for dredging 1/2 cub butter, at room temperature 1/2 cup minced parsley 1 tablespoon finely chopped chives 2 teaspoons paprika 1 teaspoon salt Melted butter Lemon juice Lemon wedges and bacon slices, as garnish

Dredge the crabs lightly with flour. Arrange them in a flat broiling dish or on a broiling rack. Cream the butter with the parsley, chives, paprika and salt and dot the crabs with the mixture. Broil the crabs about 3 inches from the source of heat in a preheated broiler 5 to 8 minutes. Baste often and turn once during cooking. Serve with melted butter and lemon juice. Garnish with lemon wedges. If desired, serve with bacon slices. From Craig Claiborne's "The Original New York Times Cookbook" JOHNNY APPLES CHARCOAL GRILLED SOFT-SHELL CRABS (4 servings) 4 tablespoons dijon mustard 3 tablespoons melted butter 8 jumbo soft-shelled crabs, dressed

Once the charcoals have stopped flaming, mix mustard with enough melted butter to get a liquidy paste. Brush on crabs. Place on grill for 2 minutes on each side. Serve immediately.