In a medium sized mixing bowl combine the sourdough starter and water. Whisk until combined.
Add flour and salt, mix until a shaggy dough is formed. Cover and let sit for 30-60 minutes.
Perform a set of stretch and folds. Cover and let sit for another 30-60 minutes.
Perform a second set of stretch and folds. Cover well with a damp towel, allow to bulk ferment until doubled- 6-12 hours.
When your dough is doubled, dust the inside of your banneton liberally with flour.
Shape your dough: Fold the edge of the dough two thirds of the way over, fold the other edge of the dough over- as if you're folding a letter. Your dough will now be a rectangle, roll up the dough into a boule starting from the short edge.
Move the dough to the prepared banneton, seams up. Pinch the seams closed. Sprinkle the top and sides of the dough liberally with flour.
Place the banneton in a large plastic bag, or cover the dough with two damp tea towels. Move the dough to the fridge to long ferment for 12 hours or longer.
When ready to bake, place your dutch oven in the oven with the lid on. Put a small cookie sheet on the rack under the dutch oven. Preheat to 500°
When the oven is preheated, turn out the dough using a sourdough sling or parchment paper. Score the dough using a bread lame or sharp knife.
Moving quickly, take the dutch oven out of the oven and remove the lid. Quickly move the dough to the dutch oven, and pour a couple of tablespoons of water into the dutch oven. Put the lid on and move the dutch oven to the oven.
Bake for 30 minutes at 500℉ with the lid on.
At the thirty minute mark, remove the lid and reduce the heat to 475°.
Bake for 20 minutes at 475° with the lid off.
Allow to cool for one hour before slicing.