Their speciality seems to be the spider crab tart which they thoroughly heat for you. The freshly battered white asparagus was also delicious. They have local IPA on tap too.
It's worth a quick visit purely for those and to see the beautiful mushroom display.
"A buzzing spot, open to the street, with dark, mould-dusted Iberian hams hanging from the wall, and a small bar piled high with artfully decorated pintxos that look like cakes in a fancy patisserie. In fact, they are created from fish, foie, mushrooms balanced on puff pastry and griddled bread, topped with decorative slithers of anchovies or guindillas (pickled chillis); and of course, they’re salty, designed to be drunk with a sharp, fresh txakoli, the local wine. You could stand here – or at least try … it’s crowded – and stuff yourself, or retire to the intimate restaurant for some of the best hake in town. Try the moist, flaking kokotxas (the chins of hake or cod, €29.50), baby squid, elvers and big fish – sole, wild turbot, bream – sold by weight and charcoal-grilled for two to share. This is a popular after-hours hangout for chefs."
— The Guardian article
> "In terms of pintxos, the fried white asparagus and the spider crab tart are two that you can’t skip, but they’ve also got a couple of great raciones (a portion larger than that of pintxos) at Ganbara as well. Wild mushrooms cooked in olive oil and topped with an egg yolk are perfect for lovers of the earthy vegetable while the grilled red prawns are scrumptiously fresh and sweet."