After reading some comments, I decided to test La Fonda. If we'd gone later, we would have had to wait as a queue developed, but we arrived at 13:40, and had no problems. We had to wait a little for the fideua (20 minutes for it to be prepared), but the waiters were very gracious and apologized about it. The waiters aren't Spanish, but Barcelona is a multicultural city, so I don't have any problems with that. The portions are huge!