Went with someone Spanish-speaking, and they have a separate 'menu para celiacos' including a menu of the day with a variety of items, tapas to fish to meats.
They also have pre-made 'regular' breads in bags served on the table, and offer gluten free bread also served in a warmed bag. There were fewer bread crumbs to worry about than usual in a Spanish restaurant, which was surprisingly reassuring.
While they didn't have any gf menu the proprietor and chef were incredibly accommodating. Probably will help if you speak Spanish as English is not spoken here. I had meatballs made of chicken and corn flour. Mulit-course meal with booze for 15 euros.