Lately I have several times made a variation of Sourdough Baguettes in which I have incorporated some whole grain flour and have formed the dough into a single boule to simplify the process.  Here is the basic recipe and process.  The last time I did this, I used KFA 9-grain blend as the whole grain flour.  I have also been using a ceramic bowl sold by KFA in which to bake the boule.

Poolish

100 g. sourdough starter

75 g. all-purpose flour

75 g. water

Dough

250 g. Poolish

150 g. whole grain flour

150 g. bread flour

1 tsp. salt

¼ tsp. yeast

140 ml. tepid water

The night before, mix together in a bowl the sourdough starter, flour and water for the polish.  Cover and let it ferment on the counter over night.  (This is a good time to refresh the sourdough starter with equal weights of flour and water.)

The next day, about 5 hours before you want the bread to be done, mix together in a large bowl the polish and all the dough ingredients.  Mix first with a dough wisk and then with a hand moistened in a small bowl of water.  Allow to rest covered for 10 minutes.  Three more times, knead the dough with a moist hand, resting 10 minutes between kneadings.  After these 4 kneadings, the dough should be a smooth ball.  Cover and allow to rise until doubled, about 2 hours.

Prepare the baking dish by lightly coating it with oil and sprinkling cornmeal on the bottom.  Punch down the dough and form it into a boule shape with oiled hands.  Put it in the baking dish and cover with plastic wrap.  Allow it to rise for another 2 hours.  About 30 minutes before baking, preheat the oven to 475 degrees, including a baking steel and a cast iron skillet in the oven.  Slash a hashtag pattern in the top of the boule to help it expand while baking.  Put the boule in the oven on top of the baking steel and put about a cup of boiling water in the cast iron skillet to form steam.  Bake for about 20-22 minutes until the crust is nicely browned and the internal temperature of the loaf is 190 degrees.  (I used a wired thermometer usually used for meat.)  Allow to cool in the baking dish on a rack for 5 minutes and then remove it from the baking dish and allow to fully cool on the rack.