http://www.sazonboricua.com/
Where she posts recipes of great puertorican dishes. In her last post she covers some of the street/beach/neighborhood food a lot of us grew up with. I took my kids over xmas and we hit some of the highlights.
That would be the ubiquitous sign that precludes running a tab.
One of the great street foods in PR are pinchos, which are seasoned pork or beef skewers cooked over charcoal and served with bread and a beer.
These were awesome
Another great place to eat in PR towns is in the local panaderia or bread/pastry/deli
where you can go for a sandwich or more fancy fair, such as white asparagus
Flan
or octopus salad
Along the beach in Luquillo there are some very well known stops for a quick or not so quick meal. We sampled a few such as pionono
(plantain stuffed with beef)
Lobster empanada
alcapurrias (see Jeannette's post for recipe)
and empanadilla (empanada) of chapin (which is a coral reef fish)
Please check out the Sazon Boricua post for excellent recipes.