S.F. Sourdough At Last!
I think I've about nailed it in my efforts to replicate Larraburu and other S.F. sourdoughs. A couple of rules must be followed:
Use AP or white "bread" flour, unbleached. I tried clear flour and white-whole-wheat flour and they didn't work for me.
It will help greatly to have a temperature-controlled proofing box.
You must use the "sponge-and-dough" method. The sponge-and-dough method is definitely a two-step process. You need to have a fully-ripened starter on hand to make the sponge. Make the sponge using refrigerated storage starter and let it ferment for 9 - 10 hours at 86 F (30 C). I used to add refrigerated liquid starter directly to the dough and proof the dough for 8 hours. That was unsuccessful.
Next make the dough and let it ferment for 8+ hours at 86 F (30 C).
Shape, slash crust and bake.
100 parts flour
50 parts storage starter
50 parts water
The proportions below will make you a nice little boule:
100 parts flour (150 g)
60 parts water (90 g)
15 parts sponge (22.5 g)
2 parts salt (3 g)