This italian sausage pasta sauce is made by browning italian sausage and then simmering it in a fresh tomato sauce. The intention is that you would use ground italian pork sausage meat (not sausages in a casing), either hot or mild and cook it the way you would cook ground beef. But if you wanted to use italian sausages in the casing, you would first brown them in a skillet, then add about a cup of water and simmer, covered, over low heat for 20 minutes or so, until the sausages are cooked all the way through. Then slice the sausages and add them to the sauce in step 6. The sauce calls for two 28-oz. Cans of whole tomatoes, but you could substitute crushed tomatoes, diced tomatoes or tomato pure.