Lithuanian rye

This recipe is from a friend's Lithuanian grandmother.  I've had no success but I'm drawn to it because it uses no starter at all, and no yeast either.  It reminds me of how some Belgian beer is made with spontaneous fermentation.  My friend assures me that it's great bread.  Very old world and she misses it dearly.  This is how it is written:1) pour boiling water over 1/3 weight rye flour and stir for thirty minutes until the mixture sweetens2) cover to cool3) add 2/3 of rye flour and knead4) keep warm for 1 to 3 days until it risesTony