What about https://en.wikipedia.org/wiki/Mycoprotein (fungal protein)?

I don't know much about it but it's intrigued me for a while. Apparently the only commercial product ("Quorn") is made in a fermentation vat with glucose syrup and Fusarium venenatum spores.

But the nutrition content is interesting: 42% protein by mass yet still has fiber and other nutrients. It's also supposed to be highly satiating.

Unfortunately, Quorn is shipped from the UK and they don't let me buy just one $10 box of it where I live.