First, fly Iberia Airlines. The food was actually good, especially an apricot tart floating in a pool of creme anglaise.
The people here know how to eat, and the restaurants know how to give them what they want. So the important thing is to avoid the set price menu, which is only a bargain if you don´t care what you eat, just about the price.
I ate one meal at a sidewalk/restaurant called Casa de Camilo. I had meltingly tender octopus tasting like nothing so much as lobster, floating in a pool of what must have been olive oil, but tasted like melted butter. Slabs of fresh crusty bread to soak up the oil, white wine, and fresh strawberries with a huge mound of whipped cream.
Wine is inexpensive, and the local aguardiente is great stuff.