Position racks in upper and lower thirds of oven; preheat to 425°F. Line 2 large rimmed baking sheets with parchment paper.
Cut 2 carrots and 2 parsnips into ½-inch-thick slices on a diagonal, then cut into half moons. Cut 2 beets and 1 onion into ½-inch-thick wedges. Cut 1 sweet potato into ¾-inch cubes. You should have about 12 cups raw vegetables.
Toss the vegetables with 3 tablespoons oil, 1½ tablespoons vinegar, 1 tablespoon herbs, ½ teaspoon salt and ½ teaspoon pepper in a large bowl until well coated. Divide between the prepared baking sheets, spreading into a single layer.
Roast the vegetables, rotating the baking sheets top to bottom halfway through, until fork-tender, 30 to 40 minutes.
