If you want to have tapas in a traditional place, I can highly recommend El Sortidor.
Located on the Sortidor square of Poble Sec, this little local bar is frequented by the locals of this neighbourhood.

It has a pleasant terrace but please also have a look inside; it’s gorgeous and typical for the modernist architecture of Barcelona. Poble Sec in general displays many modernist buildings, although they are less glamorous than the ones you might know from Antoni Gaudí. This neighbourhood shows you the working class style of modernism, and El Sortidor fits right into that display of architecture. 

As it is listed as a protected heritage building, the interior has not changed much. You can still see the original freezer where back in the days the neighbours would come and get their ice. Nowadays it does not serve as an ice shop, but with the last change of owner the bar did go back to a traditional cuisine. Tapas and Catalan dishes are on the menu here and it is all delicious. Personally, I always go for the patatas bravas here. Some say they are the best in town, for sure they’re amazing as they make the bravas sauce according to their own recipe. The daily lunch menu is also very recommendable, as you have a great 2 course menu for just 11€!

So wonder off in the streets of Poble Sec – keep your eyes open for some modernist gems – and end your stroll at El Sortidor!