Savory proof that meat is not the sine qua non of gourmet cooking. Miss Thomas happily goes far beyond the Almighty Soybean which of late seems to have become the basis of so much vegetarian faddism. She also avoids the trap of vegetable ""substitutions"" in meatless stews, casseroles, and cutlets and recommends getting away from stereotypical menus where everything revolves around the entree or main course. A Gallic touch is evident in her fondness for crepes and souffles -- including a delectable chestnut souffle with cognac guaranteed to elate Sunday brunch guests. And the cooking directions are designed not to intimidate the novice. An electric blender will be a must to prepare the creamed soups and purees but the ingredients themselves are most often classically simple and seasonings and spices are used selectively to accent, not overpower, the delicacy of artichoke and asparagus. The sludgy glutinous brown rice and wheatgerm concoctions which so entrance the organically-minded are happily omitted in favor of homemade breads made of rye and whole wheat flour embellished with herbs and berries. A garden of earthly delights.