I am obsessed with all things sourdough, and this light and airy sourdough ciabatta is one of my favorites. I'd make it every day if I could — it's that easy!
In a large mixing bowl, combine the water and starter. Add the salt and flour, then mix until everything is combined. The dough should be slightly wet and sticky. Cover the bowl with plastic wrap and let the dough rest for 30 minutes.
After 30 minutes, perform the first stretch and fold. Repeat every 30 minutes for a total of 3 stretches and folds.
Allow the dough to rise at room temperature for 4-6 hours, or until it doubles in size.
Place a clean kitchen towel on a flat tray or baking sheet, and dust it generously with flour. Transfer the dough onto it and cover it. Place the dough in the fridge overnight, or for 8-10 hours.
Immediately remove the dough from the towel while it's still cold (it gets sticky at room temp) and generously coat the top with flour. Place the dough on a floured work surface and stretch it into a 12x15 inch rectangle.
Cut the dough into 12 equal squares, about 3x4 inches each. Gently transfer each piece onto a floured baking sheet.
Preheat the oven to 475°F. Allow the pieces to rise for about 30 minutes, then bake them for 10 minutes. Reduce the heat to 450°F and bake the bread for another 10-15 minutes.
Transfer the ciabatta to a wire rack and allow them to cool for 20 minutes. Enjoy!