1) Place two baking sheets in the oven and preheat to 220°C / gas mark 7.
2) Cut all of the vegetables into 3-cm pieces. Cut the onions through the base core to keep some of the layers in chunky pieces. Toss all of the vegetables with the garlic, olive oil and salt in a large bowl. Season generously with pepper.
3) Carefully remove the heated baking sheets from the oven, brush or drizzle with olive oil. Divide the vegetables evenly between the two trays, spreading them out to ensure they don't steam while roasting. Roast the vegetables until tender and golden brown, stirring occasionally, about 45 minutes to one hour.
Cook's note: Some very large parsnips have a pithy core, which should be trimmed before cooking.
Copyright 2005 Television Food Network, G.P. All rights reserved.