If you have purchased unpackaged lentils, wash them carefully to eliminate any impurities. If they were bought in sealed bags, check that there are no larvae or parasites, where they are from and the date of collection. If they are canned, verify that the tin is not dented or swollen: it could be a sign of the formation of harmful micro-organisms. We also advise you not to overcook the cotechino sausage so as not to make it too hard and dark.