Interesting! There are some farmhouse brewers in Norway, Lithuania, and a few other places that use mashing processes that aren’t temp controlled two step processes. However, mixing cold and hot mashed wort is a pretty neat technique.

Looking at the photo, there is a lot of protein haze and sediment, which I would expect given the lack of boil, and consumption from the fermentation vessel.

Now I wonder how they were processing the grains prior to brewing.