While this article is not new, I've added a section on the more simple Roman food eaten by the poor, including two recipes for their daily staple and one of my favorite dishes, porridge, but made from wheat, instead of oats. One isn't quite so simple, as it involves honey, cheese, and egg.
Although honey is mentioned, some Romans, from the late Republican period on, would have known vaguely about sugar cane. In Book XV of his Geography Strabo (c. 64 B.C. - c. A.D. 21) mentions sugar (but not by name) from India: