Mix the starter and water together in a large bowl with a fork. Add the flour and salt and continue to mix until it comes together. You may need to use your hands to help it form a shaggy dough. Cover with a wet cloth and set aside for 30 minutes.
After 30 minutes of resting, stretch one side of the dough up and fold over the top. Give the bowl a quarter turn and stretch and pull that side of the dough up, folding over the top. Turn the bowl a quarter turn again and repeat. Repeat once more until four stretches and pulls have been made. Repeat this process 3-4 times with 15-30 minutes before each time.
Cover the bowl with a towel and let it rise on the countertop for 7-10 hours, or in the fridge for 24 hours for slower fermentation. If your kitchen tends to be warmer it may be ready in less than 7 hours and if your kitchen is cooler it may take longer than 10. It should have risen about 50%.
Turn the dough out onto a lightly floured surface and very gently form it into a round. Stretch the top side up and fold into the center. Rotate the dough and repeat until all the sides have been folded to the center. You may use a bench scraper or your hands to push and pull the dough along the counter to create tension, but only just enough to form a nice round shape.
Place parchment in a bowl and dust lightly with flour. Place your dough ball on the parchment and cover. Place in the fridge to rest for an hour. Meanwhile, preheat the oven to 500° with the dutch oven in the oven to preheat as well. Allow the dutch oven to heat for a full 50-60 minutes while the dough rests.
Use a sharp knife or a razor blade, score the top of the dough at a 35-40-degree angle cutting in about ½ inch deep. Very carefully use the parchment as a sling to transfer the dough to the preheated dutch oven. Reduce the oven to 450° and place the lid on the dutch oven. Bake for 20 minutes. When 20 minutes is up, remove the lid from the dutch oven and bake for another 20-25 minutes, until the crust has turned a deep golden-brown color and the internal temp reads 205°-210°.
Cool on a cooling rack for at least 1 hour before slicing in order to avoid the bread turning gummy.