HAS ANYONE MAKDE KWAS ACCORDING TO THE RECIPE BELOW?

[Larry Von ND]

To make the beet sour (kwas): Place 3 1/2 pounds prepared beets in a large crock or ceramic bowl. Cover with pre-boiled, lukewarm water. Add 1 slice rye bread with the crust, pushing it under the water. Cover the crock or bowl with cheesecloth and let stand at room temperature for three days. Then strain through cheesecloth, pour into a glass jar and seal it. Store in the fridge. You may eat the strained beets or discard them.

IS THERE ANOTHER WAY TO MAKE THIS? POSSIBLY WITH BAKERS YEAST, RYE FLOUR, AND THE BEETS, OR IS THE RECIPE ENOUGH?