675g Bread flour
200g Whole wheat
250g liquid starter
Start by feeding your starter with equal parts water and flour, let it reach its peak (it should double or triple in size).
Using a stand mixer, mix all the ingredients 10min on low speed. Increase the speed (4 or 5 on a kitchen aid) and mix for another 7-10min or until the dough is smooth and elastic. Let the dough relax in the mixer for 10-15min before taking it out.
Transfer the dough onto a lightly floured surface and give it a couple folds before placing it in a glass or plastic container to start bulk proofing. Keep the dough between 75-80°F (24-26°C) cover with plastic wrap at all times while proofing.
Wet your hands to stretch and fold the dough into itself by pulling it from the center and repeat this 3 times with intervals of 50min.
Transfer the dough onto a lightly flouered surface and divide it into desired size.
Pre-shape with the help of a dough scraper and bench rest (leave it on the counter covered with a towel or loose plastic wrap) for 1 hour before shaping.
Shape and place in a banneton.
Cold proof in the fridge at 39°F (3.9°C) overnight or up to 16h.
Bake in a deck oven at 456F for 20-30min or in a dutch oven for 20min with the lid on then an additional 10-15 with the lid off.