It is not clear from the article or its online references. I suspect that it is not fermentation. It sounds like the stew is kept at a simmer. Extra water is ad

It is not clear from the article or its online references. I suspect that it is not fermentation. It sounds like the stew is kept at a simmer. Extra water is added to prevent burnt food and is sterilized for drinking. New ingredients are added whenever they are ready and allowed to stew for hours before eating. Assuming that my understanding is correct this is the exact opposite fermentation, keeping the stew hot will kill all but the most hardy bacteria.