Mix all the flour with water and let the dough autolyze for an hour.

Add sourdough starter and salt and mix into the dough.

Perform 4-5 stretch and folds spaced out by 30 minutes. Let the dough rest until it has expanded 30-40% in volume.

Dump out the dough gently on a working surface. Preshape the dough into a round and let it rest for 15 minutes. Shape into a batard and place it in a lightly floured banneton. Place it into the refrigerator for the final rise.

Proofing time depends on many factors so be flexible. Observe and touch the dough instead of looking at the clock. The finger poke test is a good indicator.

Preheat the oven to 480ºF / 250ºC.

Bake for 50-60 minutes on an oven plate or baking stone or a dutch oven. Add some steam if you don't have anything to cover the loaf with. You may have to lower the heat to 430ºF / 220ºC after 20-40 minutes.

Let the bread cool on wire racks.