Dissolve the starter in the water and combine it with the flour in a mixing bowl. Cover it and leave it on roomtemperature for 45 minutes.
Dissolve the salt in a little bit of luke warm water and spread it over the dough. Knead it 3 times for 2 minutes with 1 minute rest in between. Place in a bowl and cover.
After 30 minutes perform a stretch and fold and repeat this 2 times, with 30 minutes in between. Proofing takes around 2/3 hours. Let the dough proof until it feels airy and wobbly when you press it.
Place the dough on a floured work surface and pre-shape it losely. Cover it and let it rest for 20 minutes.
Final shape the dough tightly into a boule. Flour the top and place it in a floured proofing basket with seam side up.
Let it proof for another 2 hours. Make sure you bake it before it collaps. Preheat your oven, including the tray and pizzastone 1 hour before baking.
Lower the oven temperature to 220 degrees. Remove the bread from the basket and score it multiple times. Place the bread on the pizza stone and fill the tray with boiling water. After 20 minutes, remove the tray from the oven and allow the steam to escape. Reduce the oven temperature to 180 degrees and bake for another 20 minutes so that the crust is nicely colored. The bread is ready when you sound hollow when you knuckle on the bottom of the bread. Or when it has a core temperature of 95 degrees which can be measured with a thermometer. Let it cool completely before you cut it open.
