Pecorino Romano cheese is made from sheep's milk, has a straw-whitecolor and has a sharp, salty flavor. Although it is sometimes referred to as "Locatelli" Locatelli is a brand name of Pecorino Romano. Pecora in Italian means sheep and Pecorino Romano is one of Italy's oldest cheeses. Another reliable brand is Fulvi Pecornino Romano which is very flavorful with a higher butterfat content than many other similar cheeses.
Legend has it that a shepherd filled his flask with sheep's milk before a long trip and the motion during the trip caused the milk to naturally ferment. The idea for a new cheese was born. Today most Pecorino is made in Sardina Italy. With its fine flavor Pecorino's popularity as a grating cheese has grown significantly in the U.S. Since sheep only give milk for 6-7 months a year all production must satisfy the public's demand for the entire year.
If you don't have Pecorino you can substitute: