Mix water(350g), starter(100g), bread flour(450g), and whole wheat flour(50g). Autolyse for 30mins.
Mix water(25g) and salt(10g), fold into the dough. Rest for 20mins
Strength and fold the dough every 25mins for 5 times, including 2 coil-folds.
After the last coil-fold, rest for 10mins. Then shaping. Let it bench rest for 30mins.
Final shape, then put it into banneton. Room temperature, 90mins.
Fridge, over night (and/or) day.
260c, 20 mins Then, 230c, 25mins.