Although we didn't get to try La Llibertaria for food, we found it was a fantastic cheap bar in the evenings in a convenient location. After experiencing how expensive the nightlife was near the Olympic Port, we stumbled upon this hidden gem when exploring the side-roads of Las Ramblas.
The bar is decorated with many paintings and newspapers from historical Spain (I believe it is related to anarchy although I may be well off with that). The staff we met at La Llibertaria were fantastic, and over the three nights me and friends spent at the bar, we taught some English and learned some Spanish ourselves which was a nice touch! There were many shots (chupitos!) available for just €1 and we were even made a special concoction by the bar staff for our custom.
When we return to Barcelona this year we will be sure to go back there and sample the foods!