The night before you want to make the bread, mix the biga. In a medium bowl, mix the ingredients just until combined. Cover with plastic wrap, and let sit in a cool, dry place overnight.
When you're ready to make the bread, mix the flour, yeast, and salt to combine in a large bowl. Add the water and the biga and mix (with your hands or a wooden spoon) until the mixture comes together to form a ball.
Continue to mix by hand until the dough develops some gluten structure and appears smoother in texture, 4 to 5 minutes. The dough will be very sticky (almost soupy)—never fear, that’s how it’s supposed to be! Transfer the dough to a slightly oiled bowl and let rise until doubled in size, about 1 hour.
Sift flour onto your work surface and over the dough. Gently stretch the dough onto your work surface, forming a rectangular shape. Divide the dough into two even pieces.
Line a baking sheet with parchment paper, and lightly dust the parchment with flour. Stretch each piece of dough very gently as you transfer it to the prepared baking sheet. Sift more flour over each loaf, and let rise for another hour.
Heat the oven to 475° F. Place a baking sheet in the lower third part of the oven and measure out three cups of ice cubes into a large bowl. Place the sheet with the bread onto the baking stone (if you have one), and immediately toss the ice onto the empty baking sheet. Close the oven, and bake until the loaves are deeply golden, 35 to 45 minutes. If the ciabatta is browning too quickly, lower the temperature to 400° F.
I always carry three kinds of hot sauce in my purse. I have a soft spot for making people their favorite dessert, especially if it's pie. My first cookbook, The Fearless Baker, is out on October 24, 2017.