Make the Dough
Add the active sourdough starter and water to a large mixing bowl. Using a dough whisk, stir until the starter is completely incorporated and the mixture looks bubbly.
Add the salt and stir again until combined.
Add the bread flour and use your dough whisk to mix until a shaggy dough forms and there are no dry patches of flour remaining.
Cover the bowl and let the dough rest for 30 minutes.
Stretch and Fold
Perform your first set of stretch and folds. Pull one side of the dough gently upward and fold it over itself. Turn the bowl and repeat until you've worked your way around the dough.
Cover and rest for another 30 minutes.
During the second set of stretch and folds, add half of the chocolate chips, gently folding them into the dough as you work.
Cover and rest for 30 minutes.
During the third set, add the remaining chocolate chips.
Cover and rest for another 30 minutes.
Perform one final set of stretch and folds, then cover the dough for its bulk rise.
Bulk Fermentation
Let the dough rise until it has increased in volume by approximately 75 percent.
In my warm kitchen, this took about 5 hours, but your dough may move faster or slower depending on the temperature of your kitchen and the activity of your starter.
Let the dough decide when it's ready rather than relying entirely on the clock.
Shape and Cold Proof
Gently turn the dough onto your work surface and shape it into a ball, being careful not to tear the dough around the chocolate chips.
Transfer the shaped dough to a well-floured proofing basket.
Cover and refrigerate for the second rise for several hours or up to 24 hours.
Bake
After the cold proof, preheat your oven and covered Dutch oven or bread-baking pan to 450°F.
We're not trying to burn chocolate here.
Turn the cold dough onto a piece of parchment paper that you can use as a sling to lower the loaf into the hot pan.
Score the top gently, trying to avoid any chocolate chips directly in the path of your blade.
Carefully lower the dough into your hot pan and cover.
Bake covered for 20 minutes.
Remove the lid and continue baking for approximately 40 minutes, or until the loaf has a deep brown crust studded with delicious little bits of chocolate.
Transfer the finished loaf to a cooling rack and cool for at least 1 hour before slicing.