Hello and thanks

Hi, Patrick.

Welcome to TFL!

It'd nice to see another Central Valley TFL member come on board. I'm 90 miles down the road from you.

I assume it's Floyd's Rustic Bread you want to make - the one adapted from Hamelman's "Bread." That formula uses a preferment that is called a "pâte fermentée." You want to convert it to a sourdough bread.

What I would do is make your starter so it has the same proportions of water and flour as the original pre-ferment and the same total weight. I would also leave the salt out of the starter and add it to the final dough. Presumably, you won't be adding the yeast, if you are doing a sourdough version. I would also use a smaller proportion of my mother starter in the final build.

So, if you were to have 25% of the total flour in the final starter build coming from your 100% hydration starter, your final starter build would be:

8 oz 100% starter  (which is 4 oz water, 4 oz flour, by definition.)

12 oz Bread Flour (1 lb minus 4 oz flour in the starter)

5.5 oz Water (9.5 oz minus 4 oz water in the starter)

This would give you the same total weight of starter as Floyd's pâte fermentée at the same hydration.

This should be allowed to ferment until ripe, then the other ingredients mixed per Floyd's instructions. Of course, you will remember to add 1 tsp salt to the final dough (You left 1/2 tsp of salt out of the starter, right?), and you won't need to add yeast to the dough, either.

Note that the fermentation and proofing times will be different for a sourdough than for a yeasted dough, so allow more time for the dough to double and for the loaves to proof. Watch the dough, not the clock.

I hope this helps.

David