One of the things that happens to the Dude of Food when he walks all over Rome is he begins to work up an appetite.
On my way to the Pantheon I stopped at the Habana Cafe and had a delicious and very affordable lunch.
Located on Via del Pastini 120, around the corner from the Pantheon, you can get a great lunch, served by a cool staff for less than $15 euros. I sat outside and enjoyed the historical ambiance as I ate anti pasta, spaghetti carbonara and sipped a beer.
There are other options in the immediate area but this place is certainly worth checking. Bon Appetit. Grazie Habana Roma.