Preheat oven to 400°F (200°C).
Chop root vegetables and onion into evenly-sized chunks; separate garlic cloves and leave whole.
Toss vegetables and garlic with salt and pepper; spread on a large baking sheet in a single layer.
Roast for 40-45 minutes until vegetables are tender and golden brown.
While vegetables roast, whisk together miso paste, rice vinegar, tahini, maple syrup, minced garlic, and water to create the glaze.
Remove vegetables from oven, drizzle with miso glaze, and toss gently to coat.
Serve immediately while warm.