Mix together the yeast, 100gr of water and 100gr of whole wheat flour. Cover and let it sit overnight (if you are doing it in the morning let it sit until it doubles in size)

In a large bowl put the rest of the water in the recipe, and the flour. Remember to keep around 100gr flour aside. Mix the dough with a spoon or with your hands (remember to remove any rings and nail varnish). If it is too loose, add the remaining flour. Always keep some flour handy, in case you need to add some more.

Knead the dough for a couple of minutes, then cover the bowl. Let it sit for somewhere from 30min to 1 hour (3 hours will be ok too - unless it is too hot, then 30 min. will do).

After resting the dough, start again to knead it a bit in the bowl. As you knead the dough becomes more and more elastic, then roll it into a ball and cover again. Put in the fridge to rest for 6 to 12 hours.

Remove the dough from the fridge and knead it a bit. Shape it into a log onto a baking tray dusted with flour, then let it sit until it has risen almost to double its size.

While the dough is rising, preheat your oven to 250°C (480F). When the bread is ready to go in the oven, score the surface with a sharp knife (at least 2/3cm deep).

Put it in the oven for 10min then lower the heat to around 180°C (350F) and cook for another 30 to 40 minutes. Check the bread after 30 minutes. Remember that everyone's oven is different so it might need less or more time. Some adjustments in the height of the rack might be needed.

Let the bread cool down completely before cutting it.