Bring quinoa and 2 cups vegetable stock to a boil in a medium pot over high heat. Reduce heat to medium-low, cover, and simmer until quinoa is tender, about 15 minutes. Remove pot from heat and allow to stand, covered, for 5 minutes. Fluff with a fork. Chill before assembling the jars of salad.
Vinaigrette:
In a medium bowl whisk together mustard, lemon juice, white balsamic vinegar, garlic, red pepper flakes, salt and pepper. Gradually whisk in olive oil. Set aside.
To assemble the jars:
In four quart size wide mouth Mason jars, add about 4 tablespoons of vinaigrette (you will have a bit left over for future use). You may use more, to taste, if desired, but I think this is plenty. Carefully add in the quinoa. Begin layering the vegetables into the jars, starting with the carrots, the cucumbers, corn, orange pepper, grape tomatoes, onion and then finishing with the arugula, packing it tightly.
Seal the jars with lids and refrigerate until ready to eat.
When ready to eat your salad in a jar, shake it well to dress the salad and use a long fork to get to the bottom, as you may have to “toss” it around to coat the ingredients and mix them well.