Just stop in a bar, order some simple tapas, tortilla española, jamón serrano, queso manchego, boquerones fritos, etc, and then enjoy.
Or wander down to the beach and get some paella cooked over an open fire and then get some churros and chocolate at any little cafe.
Spain has some of the greatest food in the world, but it's great because it's simple, and it's combined with the ambiance of sitting with friends, talking, laughing and enjoying time together.