Pull sourdough starter out of the fridge the night before. Leave in the oven overnight with the oven light on. Once the starter's dome has flattened out, it is fully risen.

In large bowl, whisk together water and salt. Whisk in starter until mostly incorporated. Add flour and, using bowl scraper or wooden spoon, mix until shaggy dough forms. Cover with damp towel and let rest on counter 30 minutes.

Using hands, pick up dough and fold over itself 4 to 5 times counterclockwise. Cover with damp towel and repeat folding every 30 minutes for 2 hours, replacing damp towel after each time. Let rest in warm spot, still covered, until doubled in size, 2 to 4 hours.

Lightly flour clean kitchen towel or flour sack and top with dough, seam side up and shaped into a ball. Place towel with dough in clean bowl. Cover with plastic wrap and refrigerate overnight.

When ready to bake, position oven rack in lower third of oven and heat oven to 475°F for 30 minutes. Place large Dutch oven (without lid) or cloche (with lid) on lower rack and heat for 30 minutes.

Meanwhile, on work surface lined with parchment paper, turn out dough, seam side down, and peel off cloth. Using hands, shape dough into ball. Using lame or very sharp paring knife, score one 6-inch-long slash in center on top.

Carefully remove Dutch oven from oven (or remove cloche and uncover) and add dough with parchment. Cover with lid and bake 30 minutes. Uncover and bake until crust is golden brown and crisp, 25 to 30 minutes.

Using parchment, carefully transfer bread to wire rack and let cool at least 2 hours before slicing and serving.