TAPAS! Are sweeet, but small. I think I felt full for the first time in the last month when we went to an all you can eat buffet in Madrid. Aside from quantity however, the quality of food is definitely top notch, but you'll pay for it too. The 20 euro meal at Kursaal was incredible, but how can you beat free tapas?
My second first was free... octopus, calamari, patatas bravas, etc. All were very very good, and apparently very common here. As professor Hecker compared it: fried chicken and sweet tea of Barcelona and definitely much better tasting than that. What better way to have an introduction to your class than a glass of champagne and plates full of tapas!