They're chilean sandwiches:
Lomito Palta, a thin cutlet of pork, mashed avocado, tomato, maybe mayo, onion on a roll that's a cross between a bun and ciabatta. Images all lifted from google search.
Barros luco is the same concept but with steak and green beans and cheese.
There's a ham variation that's popular too, barros jarpa
If you can find a chilean restaurant, they'll usually have these on the lunch menu and a few others too. Usually very...