Measure out culture.
Add water and stir well with fingers.
Let it rest 30 mins
Combine the 2 flours.
Sprinkle in the flour into the culture mixture reserving one cup to adjust for variances in temperature.
Let it rest for 30 mins.
Add salt
Put the dough on a flour powdered surface and slap it one time. (this will let you know if it is too sticky. If it is sprinkled in a little more flour)
Stretch and fold the dough until it resists. (approx 8 times with quarter turns)
Let it rest for 30 mins.
Repeat 3 times (stretch and fold the dough 8 times with quarter turns and let it rest 30 minutes)
On the 3rd time allow the dough to proof 2 hours at room temperature.
Move to the refrigerator for an overnight rise. (can be kept for 3 days before baking)
When ready to bake, divide the dough into 2 portions for 1 lb 5 oz batards or one 3 lb boule.
Flatten into an oval and shape, pinching seams well.
If using pizza stones place the loaves on a "slip" - you can use a cookie sheet dusted with flour. (this makes it easier to let them "slip" onto the pizza stone.)
Proof for 1 hour at room temperature.
Preheat the oven to 500.
Slash to create a design on top of the bread (straight line, cross, or star with scissors)
Place in oven and bake for 30 min for batard (long and narrow) 1 hour for large boule (round) or until golden brown.
To test, turn the loaf over and tap lightly. It should sound hollow.
Remove from the oven and place on wire racks to cool.
Allow 30 minutes to cool completely before cutting it.