In a large mixing bowl, combine the 500g of all-purpose flour and 350g of room-temperature water. Mix until there are no dry bits of flour. Let it rest for 30 minutes (this is called the autolyse).

After 30 minutes, add 100g of the active sourdough starter and 10g of salt to the dough. Mix well until fully incorporated. The dough will be sticky.

Knead the dough for about 10 minutes by hand, or use a stand mixer fitted with a dough hook for about 5 minutes, until it becomes smooth and elastic.

Place the kneaded dough into a lightly greased bowl, cover it with a damp cloth or plastic wrap, and let it ferment at room temperature for 6 to 8 hours, or until it doubles in size.

Once the dough has risen, turn it out onto a lightly floured surface. Divide it into 4 equal pieces. Shape each piece into a round loaf, tucking the edges under towards the center.

Place each shaped loaf into a floured proofing basket or bowl. Cover them and let them rest for another 1 to 2 hours at room temperature, or until puffy.

Preheat your oven to 450°F (230°C) about 30 minutes before baking. If using a pizza stone, place it in the oven while it preheats.

Carefully transfer each loaf to a baking sheet or directly onto the pizza stone. Use a sharp knife or razor blade to score the top of each loaf to allow for expansion during baking.

Bake the loaves in the preheated oven for about 25 to 30 minutes, or until they are golden brown and sound hollow when tapped on the bottom.

Once done, transfer the loaves to a wire rack to cool completely. This cooling period is essential for developing the crust.