In a large mixing bowl, combine 4 cups of flour and 1⅔ cups of warm water.
Stir until a shaggy dough forms, then let it rest for 30 minutes.
After resting, add 1 cup of active sourdough starter and 2 teaspoons of salt.
Mix well until everything is fully combined.
Cover the bowl with a clean towel or plastic wrap.
Let the dough sit at room temperature.
Every 30 minutes for 2 hours, perform a set of stretch and folds.
To stretch and fold, pull one side of the dough upward and fold it over itself.
Turn the bowl a quarter turn and repeat three more times.
After the final fold, cover the bowl again and let the dough rise for 6 to 8 hours.
It should double in size and appear bubbly and puffy.
Gently transfer the dough to a lightly floured surface.
Shape it into a round or oval loaf by folding and tucking the edges underneath.
Place the shaped dough seam-side up into a floured proofing basket or towel-lined bowl.
Cover and refrigerate for 8 to 12 hours.
The next day, place a Dutch oven into your oven and preheat to 450°F (232°C).
Remove the dough from the fridge and turn it out onto parchment paper.
Score the top of the dough with a sharp knife or razor blade.
Carefully lower the dough into the hot Dutch oven using the parchment paper.
Cover and bake for 20 minutes.
Remove the lid and bake uncovered for another 25 minutes.
Take the bread out of the Dutch oven and let it cool completely on a wire rack before slicing.
