Wow, bread is complicated. For something so ubiquitous I had no idea just how much work it is to produce a simple loaf of sourdough bread, as good as what I can buy for a few bucks.
My best attempt so far is a heroic four day recipe, based on http://www.weekendbakery.com/posts/san-francisco-style-sourdough-bread/ but increasing the hydration to produce a more open crumb. The texture of this bread is pretty much where I want it to be, but it could be a little bit more sour.
The baker’s formula for this recipe is:
Pre-ferment: 100% AP Flour, 65% water, 20% starter. Mix the pre-ferment, ferment at room temp for 9 hours, then refrigerate for 35 hours.
Dough: 85% AP Flour, 15% whole wheat flour, 75% pre-ferment, 78% water, 2.9% salt. Mix the dough and pre-ferment together, knead 3 minutes on a dough hook, refrigerate 15 hours. Then rest at room temp for 2 hours to warm up, shape the loafs, proof 2-3 hours in bannetons, bake at 550F with steam for 15 minutes, then 450F for another 15 minutes or so until internal temperature reads 200F.