Mix water and starter together.
Add flour and salt, mix with dough whisk to incorporate. Use your hands to finish mixing if needed.
Cover with damp tea towel and let rest for 15 minutes.
Do 2-3 sets of stretch and folds every 15 minutes.
After final stretch and fold, cover and leave on the counter to proof overnight.
The next day, do a final set of stretch and folds, turning the bowl as you go. Wait 60 seconds and do a final stretch and fold.
Cover with damp tea towel and refrigerate for 1 hour (or longer if you can't bake right away).
Place Dutch oven in the oven and preheat to 500°f.
Once oven is preheated, flip the dough out onto parchment and score the top.
Transfer carefully to the hot Dutch oven, and replace the lid.
Bake with the lid on for 20 minutes.
Take lid off and lower temperature to 450°f and bake for another 15-20 minutes.
Take out and let cool for 2 hours before cutting.