For the Soaker:  Combine all the ingredients for the soaker in a medium bowl.  Cover with plastic wrap and let sit at room temperature overnight, approximately 8-12 hours.

For the Dough:  Combine both flours, yeast and water in a separate bowl.  Stir to combine as best you can (mixture will be thick), and then knead briefly with your hands until you have a cohesive mixture.  Dough will be very thick and clay-like in texture. Cover with plastic wrap and let sit at room temperature overnight, about 8-12 hours.

Grease a 13 x 4 inch pullman loaf pan with butter and dust with rye flour, including the lid.  Set aside. Combine the soaker, flour mixture, salt and molasses in the bowl of a stand mixer. Fit mixer with paddle attachment and mix on low speed for 2-3 minutes until everything is thoroughly combined, scraping down the sides of the bowl from time to time.  Increase speed to medium and mix for an additional 2-3 minutes, stopping to occasionally scrape down the sides of the bowl. Mixture will be quite sticky.

Transfer the dough to the prepared pan.  Smooth out the top and sift a thin layer of rye flour over the surface of the dough.  Place lid on pan and let the dough rise for 1½ -3 hours at room temperature or until it is about ½ inch from the top of the pan.  The time that it takes for your dough to rise will largely depend on the temperature of the dough and your kitchen.