Pan de Cristal Catalan (Pa de Vidre)

Pan de cristal, pa de vidre in Catalan, belongs to Catalonia and especially Barcelona: a lean rectangular loaf with a paper-thin amber crust and an airy crumb whose walls look almost translucent. Its proper place at the table is split and toasted for pa amb tomàquet, bread rubbed with ripe tomato and dressed with olive oil and salt. What makes this loaf itself is the water. The dough carries the same weight of water as flour.

At that hydration, the mixture begins closer to a batter than any sensible-looking bread dough. Don't rescue it with extra flour. Four sets of coil folds organize the gluten into a strong net, then gentle handling preserves the bubbles that net has caught. Build the strength first and leave the air alone afterward. That's the method that decides the loaf.

Use harina de fuerza, strong white bread flour with 13% to 14% protein. Far from Catalonia, the strongest supermarket bread flour is the right substitute. If yours has only 11.5% to 12% protein, use 460g water rather than 500g; the crumb will be a little closer and less translucent, but the loaf won't collapse. My Margin says only this: don't shape what took hours to inflate. Pésalo, no lo adivines, weigh it, don't guess. Siempre sale, si lo sigues.