Combine starter ingredients. Cover and let stand at room temperature 4 hours.
Add starter and remaining ingredients to the bowl of a stand mixer. Fit mixer with dough hook. Turn mixer to speed one until well combined. (Note: it will not look like dough at this point, but will be very wet and sticky.)
Cover bowl with a clean dish towel and let stand 30 minutes. Uncover and turn to speed 1 for 30 seconds. Re-cover bowl and let stand 30 minutes. Uncover and turn to speed 1 for 30 seconds. Repeat two more times, for a total of 2 hours.
Sprinkle a little whole wheat flour on a clean work surface. Add dough and knead by hand a couple of times. Divide dough in half and roll one half out to a large rectangle. Starting with a long end, roll up into a log. Pinch seam to seal and fold ends under and pinch to seal. Place on a parchment lined baking sheet. Repeat with remaining dough.
Cover with a clean dish towel. Let stand 30 minutes.
15 min before standing time ends, preheat oven to 475.
Uncover and bake 18-25 minutes or until crust is golden brown and loaves sound hollow when tapped. Let cool before slicing.
If you crave warm bread slathered in butter like I do, you can slice the still-hot loaves if you have an electric knife. I do not recommend cutting by hand, though, until they're cool.