Clean the squid. Cut it into ring and mince the parsley. Put the onion into oil: if you like cut it in little pieces, on the contrary cut it in a half and then eliminate it. Add the parsley and then the squid. Cook for 10 minutes and then add tomatoes' sauce. Add salt and pepper as you like. Cook slowly for at least one hour. In the meantime put boiling water and cook paccheri's pasta. Add paccheri into the sauce and serve hot.