Make vinaigrette by whisking together lime juice, pepper, jalapeño, salt and olive oil. Set aside.
Place quinoa in a fine sieve and wash under running water, rubbing with hands, then drain.In a large pot, combine 1 quart water and quinoa. Bring to a boil, lower heat and simmer uncovered for about 10 minutes, until quinoa is barely tender. Strain, drain thoroughly (do not rinse) and let cool.
Toss together with the vinaigrette the cucumber, tomato, green onions, parsley, and mint. Add salt and pepper to taste.