How do you cook quinoa?
For every 1 cup quinoa, use 2 cups water. Bring water and quinoa to a boil, then put the heat on low, cover the pot, and cook about 20 minutes, until grains have absorbed all the liquid. You can also toast the quinoa in a small amount of oil before adding water to the pot, for a slight change in flavor and texture; but this is completely optional.
Be sure to rinse the quinoa before cooking in water. Quinoa has a natural coating called saponin that repels insects and birds and can create a bitter taste.
Totally agree with SKK. If you don't rinse the quinoa (three or four times through a strainer) it can taste very bitter.
I also use a 2:1 ratio of water to grain as Syronai says and rinse before hand as well. Recently I did it for our daughter's birthday. She loves couscous and we were out so I substituted quinoa. Then I added in chopped dried apricots, sliced very green olives and toasted almonds, with olive oil, maldon salt and lemon juice.
I cook quinoa a little more like pasta, in a little more than the 2:1 ratio. Once the water boils, lower to a high simmer and keep an eye on it - once the endosperm shows itself, maybe after 10 or 12 minutes, you can drain it over a fine mesh strainer. It keeps the quinoa from getting to soggy! As to rinsing, it depends on brand. Some say on the package that it doesn't need rinsing. If it says nothing at all, I rinse.
Here's an all-quinoa website. She uses a cooking technique that's a bit different, where you finish by steaming. There are lots of recipes, using quinoa in ways you may never have dreamed.
I love cooking quinoa because you can SEE, as healthierkitchen said, when it's done. I don't worry about measuring the water/quinoa ratio-- just make sure that it is at least 2:1. When you see the little curls of the endosperm, you can drain off any additional water and use it to replace a portion of the oil in a vinaigrette, or, I used to use it to replace the water when I baked bread.
The 2:1 ratio usually works. Think of using fresh apricots this time of year, to be added diced up at the last minute. I also love to add roasted slivered almonds, feta cheese, cherry tomatoes, and roasted corn.