We found the best way to deal with food on travel days was to stop at a market or food store and purchase fresh fruit and the fixings for sandwiches to eat on the train. In Orvieto, we happened to stop at an outdoor market where they were selling porchetta
(roast suckling pig), a specialty of the region.
For a couple of bucks we had two great-tasting panini
(sandwiches) which never got to the train. We were so hungry we ate them in the station! Delicious!