Can yeast be used as a main ingredient? Yeast is a fungus. We eat other fungi like mushrooms. I love the taste of bread yeast (although it's a bit expensive to make a full meal out of compared with other ingredients).

I know that live yeast produces CO2 and alcohol, which makes it unsuitable for consumption. But what about cooked yeast? Is it possible to make yeast soup? Yeast stir fry? Yeast stuffing?

Has this been successfully done before (where and how)?

Also, is the yeast which is used for making bread pure yeast? Or is it some type of dissolvable material used to carry the organisms?
I don't know that you'd want to make a full meal of it, but it sounds like you'd enjoy nutritional yeast. You can find it at any "health food store" type of grocery. It is deactivated, so you don't need to worry about it filling you up with CO2. The flavor is somewhat reminiscent of Parmesan cheese. Googling "nutritional yeast recipes" will give you plenty of ideas for what to do with it.