First make the Soaker. Mix all of the Soaker ingredients together in a bowl until all of the flour is hydrated. I found that I needed more than the original 3/4 cup of water suggested and used a little over 1 cup but this can change from flour to flour. So I would suggest using 3/4 cup water and then adding a little at a time, until you have the desired consistency. Your Soaker should be somewhat like reasonably firm bread dough in consistency. Cover the bowl loosely with plastic wrap and leave at room temperature for 12-24 hours.
Now make the Biga/ Sponge. Mix all of the Biga/ Sponge in a bowl and knead together well till a soft ball forms. Again you might need more than the originally suggested 3/4 cup of liquid; I needed a little more. Cover and refrigerate for at least 8 hours or overnight. This will keep for up to 3 days.
Two hours before you plan to mix your dough for the bread, remove the Biga from the refrigerator and allow it to come to room temperature. You might find your Biga rising a little during this time.
Divide the Biga and Soaker into small pieces (about 12 pieces each) using a sharp knife or scraper and put them in the food processor bowl (or stand mixer). You can knead this by hand too, but the dough will be tacky and a little difficult to manage. Do not be tempted to add more flour, when it is time to, than necessary.
Add the remaining ingredients for the dough, except the 1/3 cup flour) and knead for about 3 minutes. Let it rest for 5 minutes, then add as much flour as needed (if necessary) to the dough and knead for another 3-4 minutes. Your dough should now come away from the sides of the bowl but still be a little sticky but somewhat manageable. Itu2019s really important to not add too much extra flour during this step.
Place the dough in a lightly oiled bowl and let rise until almost doubled (about 1 1/2 hours). Then turn out the dough onto a lightly floured surface and pat the dough out into a rectangle with a width that just a bit less than your loaf tin. See that you do not tear the dough. Roll it up and shape into a loaf Place your loaf in a greased and floured loaf tin (I used a 9u201d by 4u201d loaf tin) and let it rise until it is just higher than your loaf tin. Bake the loaf at 180C (350F) for about 40 to 45 minutes until the top is a nice deep brown colour and the loaf sounds hollow when tapped.
Let the loaf cool completely (at least for about 2 hours), before slicing it. Refrigerate the loaf if not consuming immediately.