Mix starter with water. Add flour and salt. Combine into a shaggy dough and cover 30 mins.
Do 20 slap and folds. Rest 1 hour.
Do stretch and folds. Rest 1 hour.
Do final stretch and folds. Transfer to an oiled cambro container and use a rubberband to mark where it begins. Let it bulk ferment until almost doubled but not quite! (About 9 hours total for me in a microwave next to a cup of hot water-75-80° Remember bulk ferment begins when you mix the starter!)
Do first shaping by releasing dough onto a floured surface. Pull edges in (like a stretch and fold) to form a ball. Cup and fold to build tension. Flip over and let rest uncovered 30 mins.
Flip over and fold like a letter into center. Do a tension roll and fold side edges over. Cup/fold and lay seam side up into a banneton coated with rice flour. Place in fridge covered until the next day. 24 hours is great but 34-36 will have even more sour flavor.
Flip out onto parchment and rub top with rice flour. Score with a bread lame. Bake in a 3 quart dutch oven at 475 for 20 minutes with lid on. Remove lid and bake 20 mins more until 208-210℉ internally.
Cool at least an hour before slicing or it may be gummy.
