Pour olive oil into a mixing jar. Add 2 tbsp. lemon juice, salt, pepper, and some chili flakes if desired. Cover the jar and shake well to form a well-blended salad dressing.
In a large mixing bowl, add cooked quinoa. Mix in the chopped cucumbers, tomatoes, parsley, and mint.
Pour over the salad dressing and mix well to coat all the vegetables in the salad.