In a bowl, mix flour and water until just combined. Cover and rest 30 minutes.

Stir in the sourdough starter, then sprinkle salt. Mix until a shaggy dough forms.

Over 4 hours at room temperature, perform 4 sets of stretch-and-folds, 30 minutes apart.

Shape into a round loaf. Rest 20 minutes uncovered on the counter.

Shape tightly into a boule and place in a floured banneton. Cover and refrigerate 12–18 hours.

Preheat oven to 475°F (245°C) with a Dutch oven inside. Transfer loaf to the pot, score the top, cover and bake 20 minutes. Uncover and bake 25 minutes until golden brown.

Let cool on a rack 1 hour before slicing to set the crumb.