Rinse the quinoa in a fine mesh sieve and transfer to a saucepan. Add 2 cups of water and salt, to taste. Bring to a boil, reduce the heat, and simmer, covered, for 15 to 20 minutes, or until all of the water is absorbed. Remove from the heat, covered, and set aside for 10 minutes.
Gently “fluff” the quinoa with a fork and transfer to a large bowl. Cool thoroughly.
Add the tomatoes, cucumber, garbanzo beans, feta cheese, scallions, parsley, and mint, if using, to the quinoa and mix lightly.
In a small jar with a lid, combine 2 tablespoons each of the lemon juice and olive oil. Cover, shake, and pour on the quinoa mixture. Toss to coat and add salt and pepper, to taste. Add more lemon juice and olive oil, if desired. Cover and refrigerate for at least 1 hour before serving, stirring occasionally.
Instead of mint or basil, add 2 to 3 tablespoons of pesto. Reduce or eliminate the olive oil, as desired.