First, weight out and mill your wheat berries on the fine setting of your grain mill.
In a large mixing bowl, add water and sourdough starter. Mix well.
Add the flour and salt and mix until there is no dry flour left. The dough will be shaggy and rough.
Cover with plastic wrap or a damp tea towel and let rest for 30 minutes to an hour.
After resting, start performing stretch and folds.
To do a stretch and fold, lift up on one corner of the dough and fold it onto itself in the center of the dough.
Turn the bowl a quarter turn and continue all the way around the bowl.
Cover and let sit for 15-30 minutes and repeat.
Aim to do 4-6 sets of stretch and folds.
After the last stretch and fold, cover the bowl and let ferment for an additional 3-6 hours.
A well fermented dough will feel like it is full of air when you press it with your finger. It will also spread out into the bowl.
Prepare 4 proofing vessels. I choose to use 4 cereal bowls lined with tea towels liberally floured.
Turn the dough onto a lightly floured surface and divide into 4 equal portions.
Shape each portion into a round ball. Turn over and drag across the table to seal the seam and build surface tension.
Place the dough into the prepared proofing bowl seam side up.
Stitch the seam to make sure it stays together.
Cover each bowl with plastic wrap and place in the fridge overnight.
The next morning, preheat the oven to 450 degrees F.