"The Julia Child of Mexico? Oh dear, what nonsense." Diana Kennedy is making her way briskly across the small central square of Zitacuaro, a town of about 150,000 in the pine-forested mountains of northeast Michoacan state. "Of course I'm flattered by the comparison," she adds, "but it's totally inaccurate." I have just arrived to spend a few days at Kennedy's home, in the countryside not far from here, observing the British-born authority on Mexican cuisine—renowned cook, ethnographer, naturalist, and perfectionist—at work. The slight 89-year-old calls out to me over her shoulder as she goes; it's all I can do to keep up. We advance into the maze of the covered market, and vendors to the left and to the right call out to Kennedy as she moves from stall to stall, vocally appraising what's on offer, in a crisp British accent that seems not to have diminished in the 55 years since she first arrived in Mexico. Of some pale guavas: "These are a little over the hill. I want them greener." Of the wild mushrooms called clavitos (little nails): "Unusual to see them this late in the year. Troubling." Of a sack of chiles de arbol: "Imported from China! The flavor is not the same! And look, they're 80 pesos to the kilo; the local ones are 120. How can the farmers be expected to compete?" At the table of a seller of wild greens, Kennedy's eyes light up at the sight of quelites (lamb's-quarter). "Señora, how do you cook it?" she asks. The vendor replies that she boils them in unsalted water, drains, and then salts them. It must be sheer reflex by now, this thing that Kennedy has spent a half-century doing: collecting recipes from cooks across the vast span of Mexico, a job that is never complete.