I imagine being a vegetarian can be difficult at the best of times, especially when eating out. Here in Spain that challenge takes on a whole new twist. The vegetable sandwich/roll can include some decidedly non vegetarian content.
A typical vege sandwich will contain; ham, tuna, cheese, egg, maybe some lettuce, tomato and a corn mayonnaise.
Another classic is the humble salad, when in its vegetarian form will include tuna.
The sandwich/roll or 'bocadillo' in the picture is one I regularly buy from our local panaderia (bakery). I myself quite like them, but if you are a vegetarian, you may not feel the same.
(Normally the bocadillo from the bakery contains a little more lettuce and tomato than the one in the photo, they obviously are cutting back. Perhaps due to this crisis/recession thing...?)