Using your spatula or dough whisk, combine the starter and water in your bowl until your starter has dissolved.
Add your bread flour and salt and mix well with damp hands until you have a shaggy, but well combined dough.
Cover with a damp towel and allow to rest for 30 minutes.
Perform about one round of stretch and folds, and re-cover with your damp towel.
Allow your dough to rest from anywhere between 6-10 hours, or until your dough has doubled.
Remove your dough from the bowl and perform the first shape, allow to rest for 10 minutes.
Perform the second shape on the dough to form a tight boule, and place your boule in a proofing basket to rest from 30-60 minutes (if you are not ready to bake, place your boule in its basket inside a plastic bag to continue proofing in the fridge; it will last up to 3 days in the fridge).
Preheat your oven, with your dutch oven inside, to 450 degrees.
Place your sourdough boule on a piece of parchment paper, lightly flour the top of your boule, and score the top.
Bake your boule in the dutch oven with the lid on for 20-25 minutes.
Remove the dutch oven lid and bake for another 15-20 minutes.