Black truffle and the Truffle Fair Food and drink · Centelles, Osona, Barcelona Image of Centelles, not of the place itself. The black truffle is gathered in the holm oak woods of Osona between November and March. Centelles devotes its Fira de la Tòfona to it, with searching by dog and direct sales, and Vic hosts the Trufforum, one of the great truffle gatherings held in Catalonia. Photo: Pere López (CC BY-SA 3.0) What to see and do in Centelles