What is the best way to cook pasta made from quinoa,amaranth, and brown rice?

I've been gluten free for two decades and have probably cooked every kind of GF pasta available. The first challenge is to not expect it to look, behave or taste like wheat pasta ;-)

Use a big enough pot. Like wheat pasta it needs space. Add a little oil to the boiling water to keep it from sticking together.

If the water is boiling like crazy, bring the heat to a gentler boil. GF pasta can be fragile. If it's spaghetti the ends are probably sticking out of the water so patiently and gently immerse it.

Once it's swimming in the pot, stir a bit with a wooden spoon or silicone utensil to make sure it's not sticking together, same as with regular pasta.

Usually the package says 8-10 minutes. You have to taste it to know. Remember it will cook a bit after drained so keep it a little bit on the chewy side.

Personally I prefer combinations of quinoa and corn as opposed to rice. "Ancient Harvest" in a turquoise box is my favorite, with Barilla a close second. Just my opinion.

There is definitely a learning curve with GF cooking. You will succeed, even if it takes more than once to attain perfection!

I admit I've only been cooking gluten free pasta for about 10 to 12 years or so, but I saw some advice on a blog many years ago which has dramatically changed how I cook it.

They recommended giving it a cold water soak before cooking, and then cook in boiling water. (I don't remember if they said oiled, but use oil as it'll help with the foaming problems, as Joy mentioned. You may also want to go with slightly less water than you'd cook regular pasta so there's more room in the pot as it seems to expand more)

The exact length of the soak varies by brand and shape of pasta, but I generally go for about 10-20 minutes. It will dramatically decrease the cooking time for the pasta (especially for longer soaks), so start tasting it after about 1/2 the time that the package recommends.

What I think it does is let the outside of the pasta cook faster than the middle -- so you can actually achieve 'al dente' before the whole thing turns to mush. You can even sauce it and have leftovers the next day that aren't just a giant blob.

I've seen lots of people online recommend either washing the pasta, or even an ice bath to stop the pasta from cooking, but I find that a good drain and then quickly get it into the sauce (with the cold water soak) is enough. Especially true if you're using a jarred tomato sauce at room temperature or some other uncooked sauce which will help to cool it down some.

Note : I usually cook Trader Joe's brown rice pasta ... it's reasonably priced, and comes in a plastic bag, so I can just slit the top and pour water in (leaving it in the sink in case of spills, as it expands as it soaks). I've mostly been cooking shapes (penne or spirals) instead of strand pasta, so I don't remember if there were any issues with those sticking to each other while soaking.