I've been a couple of times with omnivores friends and I've always found a meat-free or fish-free option. I think their vegetarian "hojaldre" (savory pastry filled with veggies) is the best. Service is very nice and the atmosphere has an evident and proud leftwing decoration. Good value for money.
Updated from previous review on Tuesday August 19, 2014
Cons: don't know is vegan friendly, difficult to reach if you move by car