I make a version of this so often in the summer.
Usually, I cook the quinoa at breakfast time and then put the whole pot into the fridge so it cools down for lunch.
At lunch, I add in whatever vegetables we have in the fridge and parsley and mint.
1/4 cup of lemon juice, 1/4 cup extra-virgin olive oil oil and a pinch of salt
That’s it.
(this one had quite a lot of parsley compared to the quinoa. Usually, I don’t have that much parsley.)