Mint invigorates roasted root vegetables like potatoes, carrots, leeks, and celery root, which is also known as celeriac, in this colorful side dish.
Preheat oven to 375 degrees with racks in upper and lower thirds. On a rimmed baking sheet, toss vegetables with oil. Season with salt and pepper. Transfer half of vegetables to another rimmed baking sheet. Spread vegetables in a single layer.
Roast, rotating baking sheets from top to bottom and front to back halfway through, until vegetables are tender and golden brown in spots, 50 to 60 minutes. Transfer to a platter and toss with vinegar. Sprinkle with mint and serve.