I'm taking a two week trip to Madrid in March and having been to Barcelona before, I am going to go ahead and assume good food exists at most corners without any guidance. Having said that, if anyone has recommendations for Madrid, Valencia and Sevilla, my ears are open.
Looking most forward to eating numerous pork products.
There are a huge number of posts on here about Madrid and, if you look for some of the recommendations of Butterfly, you wont go far wrong.
Valencia is less well covered so here are a few posts from my blog about a trip last year.
It is a truly lovely city and, now it is heading towards hosting The Americas Cup, is about to come into the spotlight.
There are some definite places that you MUST not miss
1) Casa Roberto is the place for Paella. It serves the true version originating in Roman times filled with snails and rabbit. You have to book well in advance and specify which type you want. It is worth it. Make sure you have them serve it at the table rather than plate it up.
2) Casa Montana is a small bar and restaurant in the coastal area of malvarossa ( about 15 mins by tram ) and is a must visit for spectacular tapas.
3) Tasca Angel is a tiny hole in the wall on Calle Dr Rodriquez. It serves the finest sardines I have ever tried. It gets jammed packed but is well worth fighting your way into
4) Taverna De Marisa on Calle Cavelleros. A nuevo bar which offers excellent Jamon. Most of the other bars on this more touristy st are to be avoided.
OrXarta is a speciality of the region and there are many stalls from which to sample it. Great for a hot day.
Finally, do check out the market. Spanish markets are wonderous things and this is one of the best examples both in terms of building and contents.
It is a fabulous place and it is nigh on impossible not to have a great time
Hope this helps