Combine the water with the sourdough and olive oil in a large bowl.
Add the flour and salt and mix well until all the ingredients are integrated and a lumpy, wet dough is left. Cover with plastic wrap and let it rest for an hour.
With slightly damp fingers, stretch the dough and fold it. When the dough no longer stretches, let it rest covered for 45 minutes. Repeat stretching, folding, and resting for 45 minutes three to four more times.
Once the dough has risen substantially (more than half its original size) and has some air bubbles, drop it slowly onto a floured work surface.
Stretch the dough with your fingers and fold from the edges toward the center, turning and repeating until the circle is complete.
Turn the dough and form it into a ball with your hands. Roll it, making circular movements on the work surface and always bringing the dough towards you. Roll the ball as much as necessary until you achieve a smooth ball. Your dough should be soft and taut on the surface.
Sprinkle the banneton with rice flour. Place the dough upside down in the basket,and press with your fingertips to seal the "seams." Sprinkle with a little more rice flour.
Cover with the fabric lining that comes with the banneton. Refrigerate for at least 12-18 hours.
When ready to bake, preheat the oven and the Dutch over to 450°F (232°C) for 45 minutes to an hour.
Remove the banneton from the refrigerator, uncover it, and cover it with parchment paper or a silicone bread baking mat. Place one hand on the parchment paper or mat and carefully turn the basket over with the other. Place the dough on the work surface and remove the basket.
Using a lame, make a shallow cut about 4-the 5 inches (10-12 centimeters) long on the surface of the dough.
Carefully transfer the dough to the preheated Dutch oven. Cover and bake for 20 minutes. Uncover and bake for 20 more minutes. Depending on your oven, you may need to bake for 10-15 more minutes so the loaf is nicely browned.
The bread is ready when the internal temperature reads 195°F (90°C) on the thermometer.
Remove the loaf from the oven and let it cool completely on a cooling rack.
If you want to slice the whole loaf manually, wait until the next day when the crumb is firmer.