Pour the quinoa into a bowl of cold water and rub it between your hands for a few minutes to wash it. Drain and repeat until the water is clear (it usually takes 2 rinses). In a large saucepan combine the quinoa with about 6 cups of cold water. Bring up to a boil, stirring occasionally. Reduce the heat and simmer for 10 to 15 minutes, or until barely cooked. The quinoa is done when all the grains are translucent. Remove from the heat and drain well in a fine sieve. Fluff with a fork or spread on a tea towel to help it cool faster. Use at once or store in a tightly covered container in the refrigerator until ready to assemble the salad. In a small bowl, combine the lime juice, pepper, salt, and chopped serrano. Whisk together, then drizzle in the olive oil, whisking until completely combined. In a large bowl, combine the cooled quinoa with the cucumber, tomato, feta, green onions, parsley, and mint. Toss to mix, then add the lime juice mixture and toss again, until the dressing is evenly distributed. Taste for seasonings. Mound into the radicchio leaves, using them as cups, and garnish as desired with cornichons, capers, quail eggs, feta, and olives.