Preheat oven to 450 degrees. Line 1 or 2 cookie sheets with foil. Place them in the oven so they get nice and hot while you prepare the mixture.
Dice the sweet potatoes, parsnips and onion, placing them in a large mixing bowl. Sprinkle with the fresh herbs.
Drizzle olive oil over the mixture, tossing lightly until well coated. Remove pans from the oven & distribute mixture in a single layer. A single, uncrowded layer is important because this is what allows the veggies to roast & brown. If you overcrowd – they’ll steam instead of roasting. Sprinkle with salt and pepper to taste.
Roast for about 20-25 minutes, rotating & lightly shaking pans after ten minutes. When the veggies begin to turn brown and they’re easily pierced with a fork – they’re done! Remove, taste and adjust seasonings if needed.
Serve on a pretty platter – Happy Thanksgiving!