*If you must use salt, add just a little bit of sea salt to taste. What to do:
Heat oven to 425'. Brush squash with 2 Tbsp oil and season with salt and pepper. Roast cut -side down on two baking sheets until tender and caramelized, 15 to 20 minutes.
Meanwhile, bring quinoa and 2 cups water to a boil in a small pot. Reduce heat and simmer, covered, until tender and water is absorbed, about 15 minutes. Let cool, then fluff with a fork. In a large bowl, combine quinoa, parsley, feta, pistachios, remaining 2 Tbsp oil, and vinegar. Season with salt and red pepper flakes. Divide filling among squash.