The best sandwich I ever had was from a stall near the central train station in Rome - a heavily salted, whole suckling pig with herbs and a light gravy on crusty white bread. The herbs - (rosemary, garlic and I think Thyme) were pressed into the crackle and it had been grilled over charcoal. There was also a marianade and I have never been able to pin this down. I have tried a few porchetta recipes but they are never quite the same. Any ideas what the magic ingredients may be ?