The next day, mix together the dry ingredients in a large bowl.
Add the water and biga and mix until a rough dough is formed.
Tip the shaggy dough out onto a work surface and start kneading for roughly 5 -10 minutes. The dough should be smooth and soft.
Place in a lightly oiled bowl and rest for 1 hour or until doubled in size.
Tip out of bowl, shape into a round loaf, and place in a proofing basket or on a baking tray and cover. Alternatively, shape and place in a 2lb/900g loaf tin.
Turn oven on to 220C fan and put dutch oven in to heat up if using.
Rest dough for 45 minutes.
Before baking, use a lame or scissors to make a cross in the middle of the loaf, or a long slit down one side.
Place dough in dutch oven very carefully - this will be very, very hot! Bake for 20 minutes with the lid on, then remove lid wearing oven gloves and bake the loaf for a further 10- 15 minutes. If not using a dutch oven, bake for 30 minutes on a baking tray. The bread should look golden brown and should sound hollow underneath if tapped