This is a restaurant a tourist such as myself selfishly does not want to share with other tourists, though a few find their way there. It is truly a neighborhood restaurant (located in the workingclass district of Lavapies) and there is nothing fancy about this place. What recommends it are (a) the friendly staff, and (b) most of all, of course, the excellent food.
If you are searching for genuine Asturian (and Spanish) food excellently prepared and served in a relaxed atmosphere surrounded by Spaniards Casa Lastra would be a good pick. When my American girlfriend and I first visited the place - we were hunting for a good Asturian fabada - the waiters’ eyes popped out as we stepped through the door. The shock of American tourists arriving suddenly on the scene may have been too great for them. But they soon regained their composure and mustering up all their best professionalism led us to a table where we were very well treated indeed.
To see the interior, click on this: http://www.casalastra.com/inicioingles.html Nothing fancy, but this is the real deal.
Here some menu suggestions. If you like beans try a fabada asturiana. These are faba beans, of course, and they are prepared either with clams (quite delicious) or with a traditional mix of chorizo, morcilla, bacon (the fat gives it flavor) and beef. If it’s fish you want you may want to try the merluza en cidra. (hake in cider.) In northern spain they really know how prepare fish, and if you come across a merluza en salsa verde (hake in green parsley sauce) leap at the chance of trying this delicious dish which you probably will not be able to find in the United States. Casa Lastra also makes a fine cocido madrileno, that traditional mix of garbanzos, morcilla, chorizo, beef, etc. which is so associated with Madrid. http://www.notesfrommadrid.com/2008/04/14/when-and-where-to-eat-cocido-madrileno/ If done properly, it is quite delicious. And Casa Lastra does it well.
Considering how well you will be fed the final bill should not be outrageous. This is a simple, if highly popular, unpretentious place in a Madrid workingclass district. There is much history here, and I like the atmosphere of the historic, non-touristy streets of Lavapies and the Latina. If you are strapped for funds check out the “menu del dia,” the menu of the day, for a fixed and inexpensive lunch offering. These “menus del dia” are common throughout Madrid. (And, I believe, required by law.) For a reduced price you can obtain a three course meal (appetizer, entree and desert, bread, water or a glass of wine) without breaking the bank.