Let's start with how I think it should work. I think you should be able to convert any recipe by simply calculating the water and flour contribution of the starter and subtract those amounts from your recipe. In my case 238g of the starter always equals 125g of flour and 0.5 cups of water (because that's how I feed it). And of course you need to add time for the slower growing culture to do its thing.
I have been baking a lot of typical sourdough bread and I wanted to try this technique with something very different. On the bread spectrum, not much could be more different from a crusty free form hearth baked bread than an American sandwich bread baked in a bread pan. My favorite sandwich bread recipe is the American Sandwich Bread from The New Best Recipe cookbook, so that is my starting point.
I decided to start with 238g of starter, because this is the amount I normally feed. This is more or less equivalent to a cup of starter. The original recipe calls for 532g of flour: 532-125=407g flour. It calls for 1/3C warm water that I normally dissolve the yeast in, this gets removed. It normally calls for a cup of milk, but we need to decrease the liquid a bit more, call it 7oz of milk.
- 238g fed starter (fed overnight at room temperature just before using)
- 407g King Arthur all-purpose flour
- 7oz 2% milk, warmed to tepid
- 3T butter, melted and cooled a bit
- 63g honey
- 1T kosher salt
I ended up needing to add a couple tablespoons of flour during kneading to get the right consistency, but this is within normal variability.
One thing that surprised me is how long the rises took. My normal sourdough recipe takes about 2 hours, this took 4 hours. That is for each of two rises, so 8 hours of total rising time. I might try this again with double the starter, but if I do I will probably need to use nonfat dried milk to get any of the milk character into the dough (because that will double the amount of water also and force me to reduce the milk further).
The bread turned out very well. The loaf is just slightly shorter and the crumb slightly denser than the standard recipe, but the difference isn't huge. It doesn't taste like sourdough at all, it just tastes like very nice normal sandwich bread. That was a bit surprising as I would expect 8 hours of rising to generate lots of sour flavor - maybe the honey counters it.
Was it worth it? No, probably not. Eight hours for a result you can get in two is kind of silly. But it validates the conversion principle and I expect I'll try this with other recipes to see what kind of effect I get.
Get out your calculator and try your favorite recipe with sourdough starter. You might like it. But leave yourself plenty of time.