Make the leaven. Add the ingredients of the leaven in a bowl and mix together. Cover and let it sit on the counter top overnight.
Dissolve the salt. Dissolve about a 14 cup of water with salt in a bowl and stir until well dissolved
Mix leaven and water by adding the remaining water for the dough to the leaven . Use your hands to break down the leaven into the water
Add flour into this leaven water mixture and combine to form a very shabby dough
Rest the dough for about 30 mins by covering the bowl with a kitchen towel. This is the Autolyse stage where the dough absorbs the water and breaks down the starch and proteins.
After resting, mix in the salt by pinching and squeezing it into the dough. It will feel a little wet and sticky and this is fine.
Begin the folding process (6 times)which will take about 2 1/2 hours. Refer to the instructions on folding the dough above. Once done let the dough rest for 30 mins.
Shape the dough and let it rest again. refer above in the notes under shaping the dough.
Prepare your proofing bowl by lining it with a kitchen towel and generously flouring it.
Final shaping of the dough by creating cuts and patterns
Transfer to the proofing bowl and rest the dough overnight in the fridge.
Preheat oven and cast iron to the highest temperature and bake the dough for 45mins- 60 mins. Let the bread cool completely.