The description of the brewing process isn't specific to Broyhan. It's a general description of how to brew with whole potatoes. The author suggests any type of beer can be made using this method. Who will be the first to brew a Potato IPA or Spud Stout, I wonder?
To brew 24 - 26 barrels of 100 Berlin quarts [2,748 - 2,977 litres] at a gravity of 1045 - 1050º
12 bushels [346 lbs] pale malt
12 bushels [445 lbs] good, mealy potatoes which haven't sprouted
0.5 pound Irish moss
The earth is washed off the potatoes by repeatedly pouring cold water over them.
The potatoes are mashed to a pulp using a potato rubbing machine.
While this is going on, bring 960 Berlin quarts [1099 litres] of water to the boil in the kettle.
As soon as the potatoes have been pulped, mix the 12 bushels of malt into a thick paste with 360 [412 litres] Berlin quarts of cold water.
The paste is thinned slowly with another 840 [962 litres] quarts of cold water and then left to stand for an hour.
Meanwhile add the finely pulped potatoes slowly to the boiling water, stirring constantly.
After half an hour all the pototoes should be in the water.
Boil the water for a further half hour, stirring all the time to avoid the potatoes burning on the bottom of the kettle, until it becomes a thin paste.
Transfer the malt mash and the potato paste as quickly as possible to the brew kettle, stirring all the time, and leave for an hour at a temperature of 50-55º.
Bring the whole of the mash to the boil and boil for 10 minutes.
Transfer the mash to the Zapfbottich, stirring with mashing paddles.
Draw off the wort, returning it to the top of the mash until it runs clear.
Transfer the clear wort to the kettle, add the Irish moss and boil until the wort breaks.
Sparge the grain bed with hot water to remove the last of the extract.
"Der Bier-Brauer als Meister in seinem Fache" by A.F. Zimmermann, 1842, pages 63-65 and 105-106.
I assume the rest of the process is the same as for the potato-starch syrup version. The first stage where the potatoes are boiled to a paste sounds a bit like a cereal mash.
I'm not sure where you'd get a potato rubbing machine from. A large hammer might be a substitute.
Please let me know how it turns out, if you give it a try. Though, with the lack of hops and all those potatoes, it looks more like a recipe for soup than beer.
We still aren't ausgebroyhand yet. There's still Nordhäuser Broyhan to go. A bit dull, though, that one. No potatoes of any type in it.