In a large mixing bowl, combine water and sourdough starter, using your hand to dissolve the stater into the water. Add the flour and salt. Use a danish dough whisk or your clean hands to mix the dough. Pinch the shaggy dough to incorporate all of the flour. Scrape the bowl as you go. The dough will be very shaggy. If it feels really dry, add another tablespoon or two of water, and keep pinching and mixing until no dry patches of flour remain. Cover the bowl with a clean kitchen towel, and let rest for 20 minutes.

Do 1 stretch and fold rotation around the dough. Use you hand to scoop up the dough ball, and flip it over. Cover with a kitchen towel, and let rest for another 20 minutes.

Repeat the stretch and fold process all the way around the perimeter of the dough, then flip the dough over. Cover with plastic wrap, or a dough cover, and let bulk ferment (rise) at room temperature for 12-18 hours, or until the dough has doubled in size.

Flour a proofing basket really well. Pour the dough out onto a well floured work surface. Do a quick preshape. Flip it over and let it sit on your floured board for about 10 minutes. Now the final shape, then place seam side up in the prepared proofing basket. Sprinkle the top with flour, and cover with a kitchen towel. Let the dough rise at room temperature for 2-3 hours until it is puffy, and has almost doubled in size.

Preheat at 240C, then bake at 230C with steam for 20 minutes, then again at 220C dry for 30 minutes (internal temperature must reach 96-99C).