Combine the water and flour in a large bowl until no lumps remain. Set aside to autolyse for 30 minutes.
After 30 minutes, add the sourdough starter and yeast. The easiest way to incorporate the starter into the dough is with a wet hand. Run your hand under water and then pull the sides of the dough around the sourdough starter to enclose it. Continue incorporating until no more lumps of starter remain. Be gentle and try not to tear the dough! Set the dough aside to rest for 15 minutes.
Once the dough has rested again, sprinkle over the salt and incorporate it using the stretch-and-fold technique. Pull up one corner of the dough, just until you feel resistance, then fold it over the opposite side. Repeat with each corner of the dough until you have a smooth, tight ball. I usually try for 6-8 stretch-and-folds per cycle (so, in other words, I stretch-and-fold each corner of the dough 1-2 times).
After each stretch-and-fold turn the dough seam side down and let it rest for 30 minutes. Perform 4 more stretch-and-folds, all 30 minutes apart.
After you've completed five total stretch-and-folds, turn the dough out onto a floured surface and shape it into ball by pulling the dough towards you. See above for photos!
Lightly sprinkle your banneton with white rice flour and place the bread in top-down. Make sure the bottom seam isn’t coming apart– feel free to pinch it together if it seems like it may bust open. Next, cover the banneton with a clean dish towel and place it in the fridge to rest overnight.
When you're ready to bake, preheat your oven to 450°F. Place a dutch oven into the oven while preheating.
Once the oven has come to temperature, remove the dough from the fridge and turn it out onto a parchment circle. Using a pastry brush, brush the top of the dough with water and then lightly sift a layer of all purpose flour on top. Using your hands, smooth the flour until you have an even layer.
Next, using a sharp flat blade knife, or a bread lame if you have one, score the bread any way you like. Feel free to be creative with it.
Carely lower the parchment round into the dutch oven. Place the lid on and bake for 30 minutes.
Remove the lid and bake for an additional 20 minutes, or until the top is dark brown.
Remove the bread from the dutch oven and transfer it to a wire rack. Let it cool completely before slicing.