I feel duty bound to pass on a jot of possible wisdom. Whilst parked in a remote northern forest in New England taking in the placid lake waters, the silence and the fiery shades of the fall, an elderly man suddenly appeared, very elderly too with a hickory smoked wrinkled face and shaggy locks beneath  a baseball cap, his tartan jacket hanging loose on a lean frame. He was just suddenly  there and as one does, we passed the time of day. He was not inclined to move away so a sort of conversation started up and he said he was a hunter. Not an endearing thought but he spoke with great respect of the hunted. A frozen moose, he said would last him an entire winter. Well. yes. I could see that it would. Then he hushed his voice to confiding a truth. That there could have been no one within 15 miles was not the reason, he was giving me some serious advice. 

"There is something you ought know," he began, "You really oughta know the secret of a perfect moose burger." I managed not to confess that  up until then I'd never worried too much about that. "Ah," I said. " So what is it?"

"To make a  perfect moose burger," he swelled with expertise, "when ye  mince yer moose mix it - the mince - with mushroom soup powder - yer hear me? Mushroom soup powder - that's the secret."
 "Ah,' I said, "mushroom soup powder." I glanced away for but a moment, deep thought about ever mincing a moose and he was gone, that old  hunter must move like a cat.
So, I am now passing on this info in memory of an elder and an encounter I cannot forget. Profundity is relative.

Have you been on the magic moose burgers again, Priscilla?

I dread to think what you've just posted on the Cheese thread - I'm about to look.

We used to like the odd bit of profundity, didn't we? I now read Twitter (never post, I hasten to add), and am re-visiting Dowton Abbey for escapism purposes.

 I don't try to be profound any more, and am wary of profundity in others. But I did recently post something in the comments section after reading an article about the state of the nation (UK). It was in that venerable old organ, the Times of London. To my great delight (and rather pathetic pride), I got lots of "likes". Indeed, one posh old chap actually thanked me for making him laugh over his tea and toast. See, we still have our moments.

Magic moose burgers are potentially a very old recipe. Vikings were partial to a bit of dried elk on their voyages. And the image of vikings going beserker after ingesting funny mushrooms is a popular myth although almost certainly a 1960s fancification. I'm not sure how old mushroom soup powder is, though, as a product. Powdered soup dates back to at least the First World War with dried pea soup being issued for use in the trenches.

I think mushroom powder, whether specifically for soup or just as a general ingredient and flavouring, must surely have a very old and long-established history. Fresh fungi typically contain something like 90% water and are very perishable; accordingly if they are not cooked or eaten within a day or so of being picked, they need to be quickly preserved in some way. They can be pickled in brine, vinegar or alcohol, smoked, immersed in oil or frozen, but it's often far simpler, weather permitting, to just slice them thin and let them dry for a few days, whereupon they usually shrink down into small, intensely-flavoured mushroom morsels. Once well-dried fungi will readily keep for many years, yet only require just a few minutes rehydration in water to then again be immediately ready for use. Additionally drying mushrooms usually intensifies their flavour - so a little can go a very long way - and it also, like cooking them, often counters any toxicity (most 'edible' fungi should not be eaten raw and need to be cooked to be made completely digestible: drying often, although not always, has the same beneficial effect).

Dried mushrooms (whether preserved whole, in slices, as small chunks or just crumbled into a powder) provide a compact and lightweight source of flavour, protein and essential vitamins - that keeps and travels well but that can also be easily and rapidly reconstituted. As such I'm sure mushroom powder has been appreciated for millenia: by epicures, travellers relying on light-weight supplies, those preparing for lean times ahead, or just cooks who want to give their meals a rich umami favour when suitable fresh mushrooms are not in season. So-called "instant" mushroom powder has surely been "a thing" long before it was deemed necessary to augment it with powdered potato starch, xantham gum, monosodium glutamate, potassium ferrocyanide, magnesium carbonate, sodium citrate, salt, glucose, fructose, caramel and various other E-numbered additives ...  and then market it as "traditional mushroom cup-a-soup".