Mix well until all bits of flour are moistened and you’ve formed a soft tacky dough.
After your starter has doubled, place 1 3/4 cups of room temperature water into a large bowl. Add 2 cups of your active starter to the water and stir. Mix in 5 cups of King Arthur Unbleached All-Purpose flour and 3/4 cup of King Arthur Whole-Wheat flour into your bowl. Mix well until all bits of flour are moistened and you’ve formed a soft tacky dough.