Combine 600 g warm water, 240 g active sourdough starter, and 1,000 g bread flour. Mix until a shaggy dough forms.
Let the dough rest for 1 hour.
Add 40 g warm water and 20 g sea salt. Knead the dough and do slap and folds until the dough is strengthened and smooth.
Let the dough rest for 30 minutes.
Perform 4 sets of stretch and folds, each set 30 minutes apart.
Let the dough finish the bulk fermentation.
Using a bench scraper, divide the dough into two pieces.
Use the caddy clasp technique to shape your dough.
Cover bannetons and refrigerate overnight.
Preheat oven to 450°F/230°C with Dutch oven(s) inside.
Transfer dough to parchment paper or a bread sling, score, and place in Dutch oven.
Bake with lid on for 25 minutes.
Remove lid and bake for 10-15 minutes more, or until golden brown.
Cool on a wire rack for at least 90 minutes before slicing.
