As previously suggested I made a go at SJSD using commercial yeast. I used the TFL feature (where the SJSD recipe is posted) to make a half batch of dough.
Notes and Deviations from normal SJSD recipe:
1. Used 1/4 tsp of commercial yeast
2. Added yeast to 25g flour and 25g water and put it in fridge (to replicate 50g of starter called for in recipe)
3. Autolysed all of the flour for about 24 hours (was supposed to be overnight but timing got fouled up and had to go even longer)
4. Used "Jasons Ciabbatta" method with the Kitchen Aid to knead the dough after combining the autolysed flour, yeast, and salt ... I set the machine to "8" and let it go until the doughball cleared the sides and bottom, then went another 2 minutes.
5. I had intended to use the Kitchen Aid again at "8" to knead for 2 other 1-minute intervals but again life got in the way.
6. Not sure this is a deviation ...the dough went into the fridge for about 24 hours.
7. Because I wasn't able to use the KA to knead on 2 other occasions, I stretched and folded on 2 separate occasions after removing the dough from the fridge and in preparation for baking.
8. Shaped the dough into a ball and let it rise in the oven warmed to 80F for about 45 minutes. The stuff was so slack that it spread under its own weight (like the blob).
9. Shaped the dough into a batard. During both shaping events I worked the dough over pretty hard in an effort to build surface tension.
10. Warmed the oven to 80F, placed the dough on a floured surface (also between 2 towels to form a "couche" of sorts), and let rise for about an hour-and-a-half.
11. Transferred batard to parchment, let rise for another hour or so, slashed with DE razor blade.
12. Baked at 515F for ~12 minutes (with steam), then reduced oven temp to 475F and baked for 15 minutes (and a bit longer until loaf was brown).
13. I noticed the bread, upon removal from the oven, was making a high pitched squeal which I assume is the steam "squirting" out of the crust! Interesting!!
The crumb was almost a brown color, much darker than the previous loaf of SJSD made with SD starter ... because I used the KA at "8" to knead the previous loaf I'm assuming the gluten in that loaf became oxidized and did not in this loaf.
Oven spring was pretty good, not as good as the previous loaf. The slash definitely expanded but for whatever reason there is no ear or "tearing" of the crust.
Flavor is excellent. The kids love it and I do too. We polished off about 1/2 of the loaf last night.
Next time I try SJSD with commercial yeast I think I'll make the sponge a bit larger in mass.
It looks like I need to flip the dough prior to baking ... while Christmas shopping I noticed that the local Crate and Barrel sells linen dishcloths for about 12 bucks, so in the near future I'll get one. I also saw the metal batard pans at Williams Sonoma ... interesting but I'm not sure if I'm going to get one. My batards appear to be uniform/consistent in shape which is entertaining.
I'm still struggling to understand how y'all that make high hydration doughs 1) get any surface tension, 2) get such excellent oven spring, and 3) get an "ear" on your slash.