TO MONCALVO FOR LUNCH at Ametista, a very nice restaurant with a fine view and ambitious linen and place-settings: tajarin al plin, tagliarini in ragù. Dinner, however, at Tuais, curious name for a restaurant — an Italian spelling of "twice," but the reason I do not know — in the equally curiously named hamlet of Odalengo Piccolo, little Odalengo. (There is a Great Odalengo, hardly any bigger.) We ate at Tuais once before, come to think of it, two years ago; perhaps that's the reason for the name. This dinner, like that, was based on white truffle, very scarce this year. I began with ravioli filled with a nut-meat mixture and went on to carne cruda, that sweet Piemontese beef served raw and scraped, a steak Tartare in fact, with parsley and Parmesan and, of course, shavings of white truffle, and a delicious olive oil dribbled on top.