Diana Kennedy's latest cookbook continues not only her own efforts to educate American cooks to the subtlety and imagination of Mexican cooking (The Cuisines of Mexico, 1972; The Tortilla Book, 1975) but the tradition of regional and historical research associated with such authorities as Josefina VelÃ¡squez de LÃ‰on. Kennedy has traveled extensively throughout the provinces of Mexico, seeking out and recording dishes of note from Oaxaca to Chihuahua. Some are regional classics or general archetypes on which many variations can be performed. Others are either the creations or the highly individual adaptations of the gifted cooks whom Kennedy encountered. Here is a whole new wrinkle added to the dilemma of which Kennedy book to buy first. There is remarkably little duplication of previous recipes (though the material on equipment and ingredients pretty well parallels that in the two earlier books). One is tempted to run on forever listing the beauties of this collection, from such delicate and understated dishes as plain leek soup and baked chicken with almond sauce to a simple but fascinating fish-roe appetizer, a fish and shrimp sausage from Veracruz, and an Oaxacan ""barbacoa"" of lamb or mutton encased in a tamal dough and oven-steamed with sprays of fragrant avocado leaves. These treasures are interspersed with lively reminiscences and painstaking descriptions of Kennedy's labors of love--notably an impromptu apprenticeship in a Mexico City bakery. In an epoch of gastronomic hype, there are precious (very precious) few people telling us that ""perhaps presumptuously, I should like to think of my books as contributing toward the recording and preservation of an important aspect of Mexican life and culture."" Every cuisine should have a Diana Kennedy.