The Napa Valley is the great epicurean destination of California. Alice Waters and Thomas Keller are the gastronomic celebrities of the state, and the résumés of many Napa chefs include stints at Keller’s French Laundry in Yountville and Waters’ Chez Panisse in Berkeley. Nowadays, a farm-to-table culinary ethos is not a selling point, it is a prerequisite.