This is based on a King Arthur Flour recipe and uses the 6-grain blend of barley, oats, rye, wheat, millet, and quinoa flakes sold by King Arthur Flour.

I used my own sourdough starter, which is 50/50 flour and water by weight, and which was refreshed and active. I baked it in my Lodge combo cooker, which is a great way to get a good crust on a boule. Starting in the morning, I fed and expanded my starter in two increments. By early evening I had the right amount of fully active starter for the recipe and I made the dough. It had its first rise of about 3 hours and then I put it in a banneton and in the refrigerator for its second rise overnight. In the morning I preheated the oven and combo cooker and baked it for breakfast around 8:30.

I weighed out all the major ingredients (vs. using volume measurements.)

1 cup boiling water

1 cup (142g) Six-Grain Blend

2 cups (454g) 50/50 sourdough starter

1-3/4 cups (198g) whole wheat flour (I used Turkey Red heritage flour)

1-3/4 cups (205g) bread flour

2-1/2 tsp. salt

2 Tbs. (43g) honey

1-1/2 tsp. yeast

2 Tbs. vegetable oil, plus extra to grease the dough

Put the Six-Grain Blend into the mixing bowl and pour a cup of boiling water over it.  Mix well and let cool to lukewarm.  Then mix in the flours, salt, honey, yeast, and oil.  Last, add the sourdough starter and stir.  Mix with a dough whisk until all the flour is moistened.  Cover and allow to sit for 15 minutes to auto-lyse.  Then in a standing mixer using the dough hook, knead the dough until it forms a soft dough.  Coat lightly in oil, cover and allow to rise in a warm space until nearly doubled. This could take from 1-3 hours depending on temperature and the level of activity of the sourdough starter.

Remove the dough from the bowl and carefully put it into a floured banneton for its second rise. Put the banneton in a plastic bread bag, seal, and put it in the refrigerator overnight for its second rising.

About half an hour before baking the bread, put the combo cooker parts in the oven and preheatto 425 degrees.

When ready to bake, sprinkle the top of the dough with cornmeal, cover it with a circle of baking parchment, and invert it onto a plate. Slash a cross into the top of the dough.  Carefully put the dough into the bottom of the combo cooker and cover with the top. Bake covered for 30 minutes and then remove the top of the combo cooker and bake for another 15 minutes. Remove the combo cooker bottom from the oven and put the baked bread on a wire rack to cool for about 30 minutes before slicing.