Preheat your oven to 425°F. Toss sweet potatoes, parsnips, and red onion with 2 tablespoons of olive oil and 1 teaspoon of salt. Spread evenly on a baking sheet and roast for 15 minutes, then toss and continue roasting until tender and golden brown, about 10 more minutes.
Bring 2 cups of water with 1/2 teaspoon salt to a boil in a saucepan. Stir in rinsed quinoa and cinnamon, cover, reduce heat, and simmer for 15 minutes. Remove from heat, let sit covered for 5 minutes, then fluff with a fork.
Combine remaining olive oil, apple cider vinegar, maple syrup, Dijon mustard, and salt in a small jar. Shake vigorously until well emulsified. This creates a tangy, slightly sweet dressing that binds all flavors together.
In a large bowl, toss the warm roasted vegetables, cooked quinoa, fresh thyme, and sage with the dressing. Fold in the diced apple and roasted pepitas just before serving to maintain crunch and freshness.