The night before (or at least 7-8 hours) you make your dough combine 2 tablespoons (15-20 grams) of unfed sourdough starter with 46 g of water23 g of all-purpose flour, and 23 g of whole wheat flour. Mix until there are no dry bits of flour, cover loosely with plastic wrap and let sit out overnight. This will be your active starter the next morning. A drop of the starter will float in water when it is ready.
When ready to make dough, disperse the entire starter in 300 g of water in a large bowl. Add all flour and mix by hand until there are no dry bits. Then, add in the pumpkin. Knead for 1-2 minutes until well combined. Cover and let rest for one hour.
After the hour is up add salt and remaining 20 g of water. Mix well and cover the dough again.
Then turn the dough every 30 minutes for until 2 hours. This means grabbing the underside of the dough, and stretching it up and over the rest of the dough. Perform a few of these turns each time you handle the dough.
After two hours is up, let the dough rest for hour interval before you turn it again. Continue to turn for another 2-3 hours.
Then transfer the dough lightly floured work space and shape them into round like this. Fold the third of the dough closest to you inward, and then stretch the dough out to the sides. Fold the right, and then left, sides in toward the center. Fold the top of the dough inward, and then wrap the bottom part of the dough over it all. Work this into a round shape, and place seam side up in a proofing basket lined well with flour.
Let rise overnight in the refrigerator.
When you are ready to bake preheat oven to 475 degrees.
Remove the dough from the proofing basket and loosely tie the bread in crisscross with jute and transfer to dutch oven and close the lid and immediately place the top back on and return to the oven.
Turn the heat down to 450 degrees and cook for 25 minutes.
After 25 minutes remove the top of the dutch oven and rotate the pan. Continue to bake the bread for another 35 minutes, until the crust is deeply caramelized.
When you can touch the bread remove the thread from the bread. If needed place the bread in the oven for another 5 minutes and enjoy. You will get a pumpkin shaped bread.