Rinse the quinoa and add 1 and 1/2 cups water, bring to a boil, add salt, and cook for about 13 minutes uncovered. Cover, remove from heat, and let stand for 10 minutes covered (during this time the quinoa will absorb all the water; drain again if needed). Transfer to a plate and let cool.
Wash and dry the cucumbers, peel them, but leave strips of skin every half centimeter. Dice them, transfer to a large salad bowl, add tomatoes diced (with skin and seeds), onion, finely chopped chili peppers (if using), chopped chives or scallions, and parsley and mint.
Add the olive oil, lemon juice, garlic, and salt. Mix. Combine with the cooled quinoa. Can be served immediately or chilled in the refrigerator.