Autolyse: Combine flours and water 1. Rest for 1 hr.
After the autolyse add the levain, salt, water 2, then add the oat porridge and mix until fully incorporated for about 15 - 18 minutes.
Bulk Fermentation: Allow the dough to ferment for 3 hours with 1-2 folds. With wet hands pull one side up, fold it to the center, and rotate the bowl. Repeat on all four sides. Do the first fold at 45-60 minutes, and a second fold, if needed, after another hour.
Shape: Gently round them into a ball and rest for 25-30 min, dividing them into 875g portions.
Final Proof: Let it rest in the fridge 12- 18 hrs.
Bake: With steam for 20 then vent the steam and bake for another 20 min at 450- 485°F.
