Follow these simple steps to create your roasted root vegetables side dish:

1. Preheat Oven: Preheat your oven to 425°F (220°C).
2. Prepare Vegetables: In a large mixing bowl, combine the chopped carrots, parsnips, sweet potato, and red onion.
3. Add Garlic: Add the minced garlic to the bowl with the vegetables.
4. Season: Drizzle the olive oil over the vegetables. Then sprinkle the salt, black pepper, thyme, and rosemary. Toss everything together to coat evenly.
5. Arrange on Baking Sheet: Spread the seasoned vegetables on a large baking sheet in a single layer.
6. Roast: Place in the preheated oven and roast for 25-30 minutes, or until the vegetables are tender and slightly caramelized. Stir halfway through to ensure even cooking.
7. Check Doneness: Pierce the vegetables with a fork; they should be soft and fork-tender.
8. Garnish: Optional: sprinkle with fresh parsley for added color and flavor before serving.

These straightforward steps will lead you to an incredible roasted root vegetables side dish that your family and friends will love.