And also, my love of Madrid. My top picks:
Lakuntza for a great T bone steak. Start out with pimientos fritos (fried green peppers) and wash it all down with a Ribeira de Duero full bodied red wine.
Ultramarinos quintin has very good food, buzzy ambiance and a very attractive crowd. I had the  tiraditos to start and then fried halibut. Both were superb.
Paraguas, a classic Madrid restaurant with indoor and outdoor seating. Everything is tops and highly professional service.
Aranda de Duero. Don’t leave Madrid without having roast lamb and this is the place to have it (there are several branches).
Pescador, the place for fresh seafood. Not a long menu, but you can be assured everything was right off the boats.
For a quality and cheap lunch, go to the restaurant in the Mercado de Lagasca (market on Lagasca street). I had string beans as a first course, followed by sole and roast potatoes and fresh cherries with bread and wine. 10 Euros!
Buen provecho! Enjoy!