Black truffle of Bajo Aragón Food and drink · Mas de las Matas, Bajo Aragón, Teruel The holm oaks of the sierras in the south of the comarca produce winter black truffle, gathered with a dog between December and March. It is a product of high economic value used in scrambled eggs, meats and flavored oils. Photo: Diego Delso (CC BY-SA 3.0) What to see and do in Mas de las Matas