Mix and autolyze. Combine the flour, water, sugar, and starter in a large bowl and stir. Use your hands to incorporate any dry bits. Cover with a clean, damp tea towel and rest at room temperature for 30 minutes.
Add salt. After the rest period, add the salt and knead for a minute or two until everything is thoroughly mixed in. You can knead it right in the bowl or on the counter. The dough should be slightly sticky but not too wet.
First rise (+stretch and folds). Cover with a damp towel and let it rise in a warm place for three hours, reshaping the dough into a ball once per hour. Simply pull from the outside and stretch into the center as shown. There is no need to take it out of the bowl. Each time you do this, the dough will feel slightly firmer.
Add cinnamon sugar. Stretch the dough out into a circle. Combine cinnamon and sugar in a small bowl. Sprinkle on top of the dough, leaving a 2-inch border around all sides. Roll the dough into a log. Pinch seams closed. Some might escape; this is okay!
Second (bulk) rise. Heavily dust a banneton with rice flour (this works better than regular flour to prevent sticking). Place the loaf into the banneton and cover with plastic wrap. Allow to proof overnight in the fridge.
Prep for baking. In the morning, preheat oven to 425℉ with rack in the center with the Dutch Oven inside. Remove dough from fridge and turn it out onto a sheet or parchment paper, trying to have it land in the center. Slash the top with a lame or very sharp knife. Carefully remove the hot Dutch Oven and place the parchment and bread inside. Place the lid back on.
Bake. Bake for a total of 55 minutes: 25 minutes covered, 25 minutes uncovered, and then remove from the Dutch Oven and bake directly on the rack for 5 minutes to brown the crust. Bread should be 200-210℉ internally when it is done. Remove from the Dutch Oven and remove the parchment paper. Cool on a wire rack 3 to 4 hours before slicing. It will keep at room temperature, tightly wrapped, for a few days.