Trim all excess fat from the beef. Cut into as many evenly sized pieces as there are to be servings. Place each between 2 sheets of waxed paper. Pound each as thin as possible (the thinner the steaks are, the better this dish works). Brown the sausage lightly in a skillet. Add the parsley, the first measure of oregano, the garlic, onion and the first measure of salt. Mix thoroughly. Spread 2 to 3 tablespoons of the mixture on each flattened steak. Roll each steak jelly-roll fashion. Use string or toothpicks or both to keep the steaks rolled. Place the rolled steaks in the bottom of the slow cooker. Combine the tomatoes, tomato paste, the second measure of salt and the second measure of oregano. Pour over the steak rolls. Cover. Cook on the slow cooker's LOW setting for 8 to 10 hours. Serve the steak rolls with the sauce.