We had a fairly large bar at our hostel that we sold freshly made juices, fruit salads and acai w. granola during the day. We also had a local lady make us sandwiches, hamburgers and hotdogs in the morning that we sold during the day. Hamburgers and hotdogs held up surprisingly well for one day and when reheated in an oven came out pretty good.
We had an empanada machine in which we sold at least 20-30 empanadas a day.
Coupled with chips, chocolates and muesli bars our bar food trade worked quite well.
Being in Brasil the most popular drink was naturally the caipirinha but we also did well with happy hour rum and cokes and tried to have a cocktail special every night. I.E order i bunch of mint and make a bunch of Mojito's.
Hope this gives some ideas