Stir together flour and salt in a 3-4 quart mixing bowl.
Add 1/2 cup sourdough starter and 1 1/3 cups warm water to the flour.
Stir the dough with a wooden spoon until it forms a ball.
Cover with a lid or plastic wrap and let rest 30 minutes.
Remove cover and do a flip & fold - lift one edge of the dough with your hand and fold it over the top of the ball. Turn the bowl 1/4 turn and do the same thing. Keep working your way around the dough until you've done four folds.
Cover the dough again and let rest another 30 minutes. Repeat this process for a total of four times.
Let the dough sit on the counter, covered all day.
In the evening, flour a kitchen towel (one without terry) and put the dough in the center of the floured towel. Bundle up the dough and place it in a bowl in the refrigerator.
The next morning or when you are ready to bake, place a dutch oven in the oven and preheat at 500 degrees for an hour.
Take the dough from the fridge and place it on a sheet of parchment paper.
Use a knife to score the top of the dough.
Carefully lift the parchment paper into the hot dutch oven. Cover with the lid and bake 20 minutes.
Remove the lid. Turn the oven down to 475 degrees and bake another 20 minutes.
Place the finished bread on a cooling rack.