Place ½ cup warm water in a small bowl, and sprinkle yeast over the surface. Let stand until yeast is absorbed, about 10 minutes.

Combine flour and salt in a large bowl. Make a well in the center, and pour in the cold water, yeast mixture, 1 tablespoon olive oil, and biga. Stir together using a sturdy wooden spoon.

When the dough comes together, turn out onto a floured surface, and knead vigorously for about 20 minutes. Take a few 1 to 2 minute breaks if you like. Form dough into a ball and coat with oil inside a clean bowl. Cover with a towel and let rise at room temperature until doubled in size, about 1 ½ hours.

Punch down the dough by folding the edges into the center and turn it over so the top is smooth again. Cover the bowl and let rise a second time until doubled, about 45 minutes.

Turn the dough out onto a floured surface and gently flatten into an 8-inch square using the palms of your hands. Cover and let rise again.

Preheat the oven to 425°F (220°C). Place a baking stone in the oven while it preheats. Dust a baker's peel with cornmeal, and gently slide it under the dough square. Use your fingers to make a dimpled surface by pressing them about ¾ of the way down into the dough. Mist with water.

Sprinkle a little cornmeal over the surface of the baking stone. Slide the square off of the peel onto the baking stone. Mist some water into the hot oven, quickly shut the door, and bake for 30 minutes until the top is golden brown.