It was a rainy morning, as usual, in Galicia. At the weekly mercado de abastos, bustling with shoppers from nearby villages, a huge tent with communal wood tables and an enormous pile of wooden plates waited for customers to arrive, myself included. Outside, in the entrance, a line of cauldrons bubbled while the pulpeiras dipped pieces of octopus in and out—one, two, three times—before releasing them to the boiling depths.…