Mix the Dough
In a large bowl, whisk together the water and active sourdough starter until fully incorporated. Add the flour and mix, with hands, until a shaggy dough forms.

Rest 
Cover and let the dough rest for 30 minutes.

Add Salt & Stretch and Folds
Sprinkle the salt over the dough and perform your first set of stretch and folds.
Continue with 3 more sets of stretch and folds, spaced 30 minutes apart (4 sets total over the course of 2 hours).

Bulk Ferment
After the final stretch and fold, cover and allow the dough to bulk ferment at room temperature for 6–8 hours, or until doubled in size.

Shape & Cold Proof
Shape the dough into a loaf (see video here). This is where you will add any add-ins you are wanting. Place it into a proofing basket and cover with a towel.
Transfer to the refrigerator and cold proof for 1–12 hours. (Overnight is what I do)

Preheat Oven
When your ready to cook, place a dutch oven into the oven and preheat to 450°F (232°C).

Bake
Once heated, carefully remove the dutch oven.
Place the loaf onto parchment paper, score the top, and transfer it into the dutch oven. Add a few ice cubes along the sides (behind the parchment so it’s not touching your loaf) for steam and cover with the lid.

Bake for 35 minutes with the lid on.

Remove the lid and bake for an additional 10 minutes, until deeply golden.

Cool
Remove the bread from the Dutch oven and allow it to cool for an hour before slicing.