I loved the tapas throughout southern Spain. Croquettes, Spanish Omelette, Patatas Bravas, the cheese varieties and olives were my favourites, but they're all wicked. The regular bodega / bar / restaurant will usually have tapas on their menu for as little as 2-3 euros.
The Francesinha is a highly revered dish native to Porto, Portugal. However I personally didn't love it, although many do.
Ceský Guláš or the Czech Beef Goulash is a must when in Prague.
The pizza and pasta is obviously great throughout Italy, but the closer to Naples you get, the better the pizza is.