This posting is for a variant on Overnight 40 Percent Whole Wheat Bread, with two key changes.  First, I wanted to start and complete the bread in one day.  Second, I wanted to use some of my 50/50 sourdough starter.  This took about 7 hours end to end and turned out a fine loaf of bread, with a good crust and a moderately open crumb.  It would be suitable for a sandwich bread.  It was 30% whole wheat.

250 g. bread flour

150 g. white whole wheat flour

200 g. sourdough starter (50/50 all-purpose flour and water)

300 g. water

2 tsp. salt

3/8 tsp. yeast

Oil and cornmeal for baking dish

In the bowl of a stand mixer, mix together the flours with a dough whisk.  Add the water and whisk until a rough dough is formed.  Cover and let it rest (autolyze) for 30 minutes.

Sprinkle on top of the dough the salt and yeast, and mix with the dough hook until a smooth dough is formed.  Cover the bowl.  For the next 2 hours, every thirty minutes stretch, and fold the dough with a wet hand for about 30 seconds and then recover the bowl.  After 4 foldings, cover the dough and allow it to ferment undisturbed until doubled, 2-3 hours.  (It was about 2 hours on this batch.)

Oil a ceramic boule baking dish and cover the bottom with coarse cornmeal (grits, polenta, etc.)

Lightly flour the dough and put it on a lightly floured surface.  Fold it a few times to degas it and form it into a ball.  Put the ball of dough in the baking dish, smooth side up.  Cover, and allow to rise for an hour. 

Put a baking steel in the oven on the middle shelf and put a cast iron frying pan on the lower shelf.  Heat the oven at 475 degrees for 30 minutes.  By this time the top of the dough should be about even with the top of the baking dish.  Heat up a cup of water to boiling.  Slash the top of the dough with a hashtag pattern, and put the dough in the oven.  Carefully pour the boiling water into the frying pan to create steam.  Bake for 30 minutes until nicely browned.

Remove from the oven and allow to cool for 10 minutes in the baking dish.  Then remove it from the dish and allow it to cool fully on a rack before cutting.