Cook quinoa: Rinse quinoa under cold running water really well. In a pot add quinoa, pinch of salt and 2 cups of water and bring to a boil. Reduce heat to medium-low, cover, and simmer until quinoa is tender, about 10 minutes. Remove from heat and let stand, covered, for 5 minutes. Fluff with a fork and spread out on a baking sheet to slightly cool, about 10 minutes.
Meanwhile, in a large bowl make dressing: whisk together olive oil, balsamic vinegar, salt, pepper and shallots.
Once the quinoa has slightly cooled, to the large bowl add quinoa, cherry tomatoes, feta, mint and arugula. Toss to combine. Taste and adjust seasoning.
You can prepare the quinoa, dressing and chop all the veggies 1 day ahead of time.
We enjoyed eating this both warm straight after making the quinoa, or after the quinoa has been completely cooled. Either way works, and just depends on your preference.