We spent two days in Jaca in which we had lunch at the Tasca de Ana on both days!
The Tasca de Ana is no bigger than a shoebox and the space around the bar is so crowded with people even the waitresses can barely get past - however the space seems to magically expand to fit more people on and we were shown to a table both times we dined and sat very happily amongst the buzz of this very Spanish establishment.
The food was so well priced and so delicious that we had really gone to food heaven! The waitresses did not force us to speak English or choose from an English menu like in some other establishments, instead letting us look at the Spanish menu and trying to explain to us what the things we hadn't heard of were. Towards the end of our meal we were choosing food at random in any case because everything was so delicious and reasonable that it hardly mattered what it was! Tapas are brought out around 5 minutes after you order them so you can start off with a couple and then order more until you are full. We never felt rushed or pressured to move on despite how busy the restaurant was. It was a real gem.
If you want to try La Tasca de Ana but fear not getting a table for dinner I would heartily substituting dinner for lunch where you are more likely to get a table but where the atmosphere is so hearty it might as well be dinner!
If you own or manage La Tasca de Ana, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.