You'll need to begin this recipe 2 days ahead.
"While working in a bar in the Aragonese Pyrenees, the mother of the owner, Aurora, explained there was only one way to make ajo arriero and that was her way. She'd start holding a potato in one hand, a stubby yet cruelly sharp knife in the other, then, in a blur of motion, would score the potato one way, then the other and, as she did, wafer thin slips of white potato flesh would fall into the pan. She would pass the knife and a potato to us and watch as we'd hack away, barely missing our thumbs. Once she'd left the kitchen we'd sneak out the old wooden chopping boards and thinly slice the potatoes in a slightly safer way.
Ajo arriero is a rich, chunky, wet dish served cold - like a tuna and egg salad with mayo, but made with salt cod and potato. The name comes from when the wealth of Spain was transported across the mountains and valleys on the donkey's back. Wool, olives, cheese and clothing were moved from maker to buyer on mules led by equally obstinate mule drivers. At the end of a long day, while the donkeys fed on pasture, their masters would cook a meal made from the durable salt cod and some potatoes that they carried with them thickened with a few locally garnered eggs. At MoVida we stuff this mix into Piquillo peppers and deep-fry them, but you can serve this as a tapa on a slice of toasted sourdough." - Frank Camorra, MoVida