Place quinoa in a bowl, and cover with cold water. Let sit for five minutes; drain through a strainer, and rinse until water runs clear. Bring 3 cups water to a boil in a medium saucepan. Add quinoa, bring back to a boil and reduce heat to low. Cover and simmer 15 minutes, or until quinoa is tender and translucent; each grain should have a little thread. Drain through strainer, and return quinoa to the pan. Cover with a clean dishtowel, replace the lid and allow to sit for 10 minutes (we skipped this step, and used the quinoa after cooking and draining).
Meanwhile, place the finely diced cucumber in a colander and sprinkle with salt. Toss and allow to sit for 15 minutes. Rinse the cucumber with cold water, and drain on paper towels.
Combine chopped tomatoes, chiles, cilantro (if using), lime juice, vinegar, and olive oil in a bowl. Add cucumber and season to taste. Add quinoa, toss and serve with avocado garnish.
*Martha Rose Shulman, New York Times