Preheat your oven to 400°F and line a large baking sheet with parchment paper or foil for easy cleanup.
In a large bowl, combine the carrots, parsnips, beets, and red onion wedges. Drizzle with olive oil and toss until everything is evenly coated.
Sprinkle brown sugar over the vegetables and add the minced garlic, salt, pepper, and balsamic vinegar. Toss again to distribute everything evenly.
Spread the vegetables in a single layer on your prepared baking sheet — don't crowd them, or they'll steam instead of roast.
Roast for 30 minutes, then flip each piece with tongs and continue roasting for another 15-20 minutes until edges are deeply caramelized and tender when pierced with a fork.
Remove from the oven and let rest for 2 minutes before serving — this lets the glaze set slightly.