How do I make authentic Russian black bread? I am interested in making the dense pungent black bread that is traditional in Russia. Recipes for black bread are varied and seem to disagree with one another. Too many of them make spongy, pumpernickel-like loaves which, while good, are not what I'm trying to make.

Is Russian black bread always made with a sourdough starter?

Some recipes have called for cocoa powder or coffee to darken the loaves as just rye flour will often turn out gray instead of dark dark brown.
Are such additives common in traditional black bread recipes? If not how is the dark color obtained?
The primary coloring agents in a traditional black Russian loaf are molasses and dark rye flour.