For more than twenty years, Barefoot Contessa, the acclaimed specialty food store, has been cooking and baking extraordinary dishes for enthusiastic customers in the Hamptons. For many of those years, people have tried to get the exuberant owner, Ina Garten, to share the secrets of her store. Finally, the energy and style that make Barefoot Contessa such a special place are shown here, with dozens of recipes and more than 160 breathtaking photographs, in The Barefoot Contessa Cookbook.          Ina's most popular recipes use familiar ingredients, but they taste even better than you would expect. Her Pan-Fried Onion Dip is the real thing, with slowly car-amelized onions and fresh sour cream. Tomato soup is created from oven-roasted tomatoes and fresh basil to intensify the flavors. Meat loaf is as good as your grandmother's, but it's healthier because it's made with ground turkey and fresh herbs. The light and flaky Maple-Oatmeal Scones are baked with rolled oats, whole wheat, and real