https://www.thekitchn.com/how-to-make-sourdough-bread-224367
Only things I changed is that I didn't take the starter out of the fridge for long before doing the leaven (unneeded imo) and I didn't need to cook it as long as she said because I used a cast iron dutch oven which retains heat amazingly well. The fancy swirls are from what is called a banneton. Not needed but cool.