To cook the quinoa, combine the rinsed quinoa and water in a medium saucepan. Bring the mixture to a boil over medium-high heat, then decrease the heat to maintain a gentle simmer. Cook, covered, until the quinoa has absorbed all of the water, about 15 minutes at a low simmer. Remove the quinoa from the heat and let it rest for 5 minutes. Fluff with a fork, place in a serving bowl, and cool to room temperature or refrigerate overnight.