In a mixing bowl, combine 500 g of bread flour and 350 g of room temperature water. Stir until no dry flour remains, then let it rest for 30 minutes. This is called autolyse and helps develop gluten.
After the autolyse, add 100 g of active sourdough starter and 10 g of salt to the dough. Mix by hand or use a dough scraper until thoroughly combined.
Knead the dough in the bowl or on a floured surface for about 10 minutes until it becomes smooth and elastic.
Place the dough in a lightly greased bowl, cover with a damp cloth, and let it rise at room temperature for about 6 to 8 hours, or until it has doubled in size.
After the first rise, gently turn the dough out onto a floured surface and shape it into a round or oval loaf. Use the dough scraper to help maintain its shape.
Transfer the shaped loaf into a lightly floured banneton or a bowl lined with a floured cloth. Cover with a damp cloth and let it rest for another 1 to 2 hours.
Preheat your oven to 450°F (230°C) with a Dutch oven inside for about 30 minutes.
Once preheated, carefully remove the Dutch oven, and place the dough into it. Score the top of the loaf with a sharp knife or bread lame to allow it to expand while baking.
Put the lid back on the Dutch oven and bake for 30 minutes. Then, remove the lid and bake for an additional 15 minutes, or until the crust is golden brown.
Carefully transfer the bread to a cooling rack and let it cool completely before slicing.