Cook quinoa with water as directed on packaging. Transfer to a large mixing bowl, cover and let chill in the fridge.
Place all dressing ingredients in a blender or smoothie maker and blend until smooth. Set aside.
Rinse, seed, and dice bell peppers and cucumber. Finely chop the onion. Roughly chop the fresh herbs.
Add the diced veggies and chopped herbs to the cooked and chilled quinoa. Pour the prepared dressing on top and stir with a large spoon to combine. Taste and season with additional salt and pepper, if needed. Serve right away or store covered in the fridge. It will be just as good hours later or the next day.