Step 1: Preheat the oven
Set your oven to 400°F (200°C). Line a large baking sheet with parchment paper for easy cleanup.
Step 2: Prepare the vegetables
Peel and chop all the root vegetables into evenly sized pieces (about 1 inch thick). Keeping the pieces uniform helps them roast evenly.
Step 3: Season the vegetables
In a large mixing bowl, toss the carrots, parsnips, sweet potatoes, beets, and onion with olive oil, rosemary, thyme, garlic, salt, and pepper. Make sure every piece is lightly coated in seasoning.
Step 4: Roast to perfection
Spread the vegetables evenly in a single layer on the prepared baking sheet. Roast for 35–45 minutes, flipping halfway through, until the vegetables are tender inside and caramelized on the edges.
Step 5: Finish and serve
If desired, drizzle with balsamic vinegar before serving for extra depth of flavor. Serve hot as a side dish for roasted meats, poultry, or as a hearty vegetarian centerpiece.