What Bracha do you make on Quinoa?
While in the culinary world it's treated sortof like a grain, it's neither the five grains recognized by the Talmud (wheat barley spelt oat* rye), nor the two semi-grains (rice and millet); so to the best of my knowledge, you'd treat it just like beets (quinoa's closest edible cousin) or peas or any other vegetable: ha'adama as it grows from the ground (and is annual, not perennial).
If you ground it or pureed it to the point where it didn't look like anything but a mush, it would then be shehakol (no different than if you pureed peas). But if you sit down to eat a plate of cooked quinoa, just ha'adama before (and borei nefashot afterwards).
I know when I've done this, my brain has gone, "Huh? It looks like rice? Really, no mezonot?!" But that's the halacha!
'*' Disclaimer: oats are generally understood to be in the Talmud's list, but some scholars question if that's an accurate translation of the Talmud's term. Here I'm going with the standard practice, to include oats.
There is a lengthy and extremely detailed shu"t (responsum) by the Chief Rabbi - HaRav Mordecai Eliyahu on this issue that reviews the history of quinoa and concludes as Shalom notes - that it is borei peri ha'adama.
Bracha Rishona: Hoadama
Bracha Acharona: Borei Nefashos