1Mix sourdough starter and water in a bowl with a whisk until it reaches a frothy milk consistency.
2Add bread flour and salt to the liquid mixture and stir with a plastic spatula, finishing by mixing and kneading with a wet hand.
3Cover the bowl with a wet towel and let the dough rest on the counter for one hour.
4Perform a set of four stretch and folds on the dough by pulling the dough up and giving the bowl a quarter turn for each stretch, then cover and let the dough rest for 30 minutes.
5Repeat the stretch and fold process twice more for a total of three sets, letting the dough rest for 30 minutes between each set.
6Cover the dough with a wet towel and let it rest on the counter for 4 to 6 hours until it doubles in size.
7Flip the dough out onto a surface, stretch it into a rough rectangle, fold it into thirds both ways, and shape it into a ball by pushing and pulling the dough.
8Let the dough rest on the counter while preheating the oven and Dutch oven to 450 degrees Fahrenheit.
9Give the dough one final shape, score the top with a wet bread lame, place on wax paper, and transfer into the preheated Dutch oven.
10Bake in the oven at 450 degrees Fahrenheit for 25 minutes with the lid on, then bake for another 25 minutes with the lid off.