Put some bacon-fat, or any pieces of fat, in a saucepan with onions, carrots, herbs, etc., all chopped up, and a little sugar. Fry them slightly. Pour off the fat. Cut up some tomatoes, add a little stock, and simmer it all together till the tomatoes are cooked. Pass the whole through a sieve, so that the sauce may be quite smooth. Boil the spaghetti separately till quite tender, then drain off the water, and mix with the tomato sauce. If cheese is liked, mix in some grated Parmesan the last thing before serving; also a little fresh butter, which can be added without the cheese if preferred.