As we know (and by “we,” I merely mean people who happen to know this), Chinese soy sauce is made by infecting boiled soybeans with a mold called Aspergillus sojae and then soaking them in salty water until everything turns dark brown. During the Middle Ages, the Middle East made something that tasted quite the same using raw barley dough.
It was called murri, from the Greek halmyris, “brine,” because it descended — as did Chinese soy sauce — from the widespread ancient practice of using pickling brine (derived from the making of ham, salt fish and the like) as a flavoring. How mold and barley, or soybeans, for that matter, got involved in the recipe is lost in the mists of time, but one medieval Moorish cookbook refers to a distinction that was still being made between “bread murri” (soy sauce) and “fish murri” (a fish sauce like Thai nam pla).
Murri is extinct in today’s Middle East, but we have a number of medieval recipes for it. You might want to give it a try. The rotting process is ghastly to behold, but I once took a batch to a lab which pronounced it pretty much carcinogen-free, and I think we can assume that people weren’t getting sick on it during all those centuries when murri was made.
The process starts with gathering broad plant leaves (a major landing place for mold spores); fig leaves are ideal. They must be fresh — because of preservatives, bottled grape leaves don’t work. And you have to obtain barley flour; usually you must make it yourself by grinding barley in a grain mill or the like. Then add enough water to make a dough you can form into doughnut shapes about 3 inches in diameter. Wrap the doughnuts with the leaves (the upper part of the leaf touching the surface) and put them in a loosely lidded container for a couple of weeks.
After 10 days or so, they should be covered by what the Arabic recipes refer to as “that which resembles spider webs” and mycologists call the “arachnoid net.” This, and the smell of rotting leaves, will confirm the presence of Aspergillus molds. As soon as the barley doughnuts have dried hard and are all green and black with mold, you pick off the leaves and break the barley up into pieces — the only difficult part of the procedure. Smashing into smallish pieces with a sledge hammer (in a confined space so not too much gets lost) and then blitzing them in a food processor is my technique. I wear a gauze mask, just because the air will be swirling with green mold spores.
Then mix 2 parts rotted barley with 3 parts salt and 3 parts water and put the bowl out in the open — recipes say to put it on your rooftop in the hottest part of summer — and leave it for a couple of weeks, or as long as you like, stirring it up twice a day and adding water as needed.
Voilà: It will turn brown and taste like soy sauce: not strong tamari soy but your everyday Kikkoman type. The Middle Eastern way was to flavor it with spices — fennel, saffron, caraway, fenugreek and nigella are mentioned in various recipes — and then to press out a liquid sauce. You will feel a sense of accomplishment, and you may also have enjoyed grossing out your friends during the rotting process.