When a wealthy Palm Beach matron throws a party -- which she does pretty often -- you can bet you won't find her in her kitchen six hours before the big night rolling hundreds of tiny pigs into hundreds of tiny blankets. More likely, she'll be perusing the flats of refrigerated finger foods in the cooler at C'est Si Bon (mini quiches, fig and cheese flatbreads, Palm Beach cheese balls, bite-sized beef Wellingtons). And when it's the cook's day off and Milady wants a no-fuss lunch -- something like roast tenderloin of beef with horseradish Dijon sauce and potatoes boulang�re -- she isn't going to Albertson's deli for her prepared foods. That's why this tiny gourmet shop in the Bradley House Hotel has triumphed through many decades, several changes of management, and the vicissitudes of fortune -- the owners have learned to satisfy a clientele a bit on the demanding (they'd call it "discerning") side. Well, there's no law saying we all can't take picky advantage of lunch specials like jumbo lump crab cakes with remoulade sauce; or red pepper meatloaf with mushrooms, or braised lamb shanks, curried new potatoes, and pea salad; or roulade of turkey, peppers, spinach, and mushrooms. In fact, a trip to C'est Si Bon on a Saturday morning to fill the picnic hamper with cream of watercress soup, maple Dijon-glazed corn beef, dilled chicken salad, and orzo primavera is an ideal first step for a trip to the beach, a pleasantly strollable three blocks up the street.