In the evening of day one mix the starter, flour and water in a medium sized mixing bowl, cover and rest overnight or at least 12-24 hrs.
On day two add the remaining flour and water, cover and rest again for the autolysis for 4 hours.
Now start the bulk: Put your dough onto a heavily floured working surface. Carefully pat into a rectangle and fold each of the corners into the centre, trying to incorporate as much air as possible. Turn the dough upside down and place seam side down on your working surface. Cover with a floured tea towel and let it rest for 30 minutes before following the given procedure again. Continue to do so every 30 minutes for the next 4 hours.
After the final turn either place your loaf on a lightly floured working surface or in a parchment lined baking pan. Cover with the tea towel and let rest overnight or at least 12 hrs.
Preheat your oven to 250 °C for one hour. 15 minutes before the time is up put a deep oven proof pan filled with water onto the lower rack. Slash your loaf. Bake for 20 minutes.
Remove the water pan, lower temperature to 200°C and continue baking until the crust is dark brown and the bottom sound hollow when tapped. Remove and let cool for at least 20 minutes before slicing. Freezes well.