Quinoa is showing up on more supermarket shelves in the United States, Canada and Europe, but—depending on where you live—you might have to seek it out in a specialty or organic grocery store. Try to find a package containing seeds that have had their waxy outer coatings removed through rinsing or some other process.
If you buy quinoa with its coating still on, you must rinse it vigorously in a strainer, then soak it for several hours in water, then rinse it again. If you leave behind any of the coating, which is full of a bitter substance called saponin, your quinoa will taste terrible.
Fortunately, most commercially marketed quinoa sold in North America and Europe today has been pre-processed to remove the coating.