Well , I´ve lived here for over 5 years and never been to Asador Donostiarra but the website (
http://www.asadordonostiarra.com/ ) has made my mouth water . There are many Basque restaurants in Madrid . I would make sure you have LOTS of money with you . On the homepage I see the owner hugging the King of Spain IN the restaurant ( photo on the wall ) . Tetuan is an interesting area very influenced in parts by Arabic tradition .. restaurants , supermarkets etc .
Maybe you would want to consider going to a traditional Madrid restaurant to have the famous " Cocido Madrileño" ... Have a look at
www.labola.es .
By the way , go to the "galería" area of the Asador Donostiarra´s website ... David Beckham , Placido Domingo , Cristiano Ronaldo , Pau Gasol , La Duquesa de Alba ( richest woman in Spain ) , Tom Cruise ......... This restaurant demands serious money !!!!!!
P.S . Lucky you living in Padova ! I hear it´s beautiful