What is your favorite food in Spain? Favorite restaurant?

Probably paella. Second might be the wonderful roasted baby pigs. Tapas is very popular, if you want to qualify that as a single "food".
If you want a favorite restaurant, you certainly have to narrow down the field to a city at least.

I'll go with Trippas a la Madrileno (tripes - Madrid style), camaron or pollo en ajo de oliva (prawns or chicken in garlic and olive oil) and churros con chocolate (deep fried sugared dough dipped in fresh hot chcolate).

I like a couple of eating establishments, depending on the city.

Oh, also can't go wrong with a nice glass of sparkling Cava or a crisp albarino and some hearty reds from Ribera del Duero or Priorat.

Sorry, you got me tripping on Spanish food now.

Pescado de sol, garlic soup, and paella.

And of course, the wine--yes, the wine. Don't think I had ever had a bottle we didn't like there! And there's a cava (like champange) I really like--Freixenet Brut--inexpensive and delicioso--we get it here in the U.S. as well.

So many restaurants, but offhand El Caballo Rojo in Cordoba and Maribel's in La Manga come to mind.

I am leaving for Spain on Sunday...

Paella a la Marinera;

Merluza a la Vizcaina (baked Hake in salsa verde);

Pez Espada a la Gallega (Swordfish grilled w/lemon juice & melted butter);

Gambas a la Plancha (Large shrimp griled as above);

Favada Asturiana (Fava beans in a sort of stew with Chorizo, Morcilla and Lacon - a hearty plate of this may make you feel like you have eaten a Brick)

potata bravas and spinach and garbanzo dip!

Gambas al ajillo! We kept having to go back to the Casa del Abuelo tapas bar in Madrid to have more of this-- it's shrimp cooked in oil with LOTS of garlic and spicy pepper.

I also loved "espinacas con pasas"-- spinach cooked with garlic (is there a trend here?) and raisins.

All of the above. Also jamon serrano, and membrillo (quince paste) with manchego cheese.

Jamon serrano, as mentioned above, and Fritura de pescados.

Angulas a la BILBAINA....BABY EELS IN GARLIC SAUCE

Oh, how could I forget! Coquinas (tiny clams), esp. those from Modesto in Sevilla. Mmmm....

Churros and thick hot chocolate!!

Romesco Sauce on Lobster rocked my world!
I dream about it.
This was very popular in Barcelona Restaurants. Does anyone happen to have a great receipe for this? I know it is made with almonds, tomato, olive oil and garlic , but with a great receipe, I would consider cooking this sauce.

I am with Lesli - coquinas at Modesto in Sevilla. Be sure to spend a few minutes having a wine at the bar inside and enjoy the action in the kitchen. It is amazing. Also bocarone [flash-fried tiny fresh sardines]. Be sure to try bacalao - it is truly amazing what they do with a piece of dried cod as hard as a shoe sole.

Restaurants:Modesto, Cunini in Granada, the Red Pony in Cordoba, Figon de Tinin el Mayor in Sepulveda [south of Valladolid], Posada de Javier in Torre Caballeros [just north of Segovia], and Mirador del Donano in Sanlucar de Barrameda.