In a large bowl, combine oil, salt, pepper and diced vegetables. Stir everything together to coat well.
Transfer vegetables to lined sheet pan and roast in oven for 30-40 minutes or until golden brown. Stir once or twice during roasting.
If cooking different kinds of vegetables together, make sure to cut the harder vegetables (such as carrots, parsnips or beets) smaller than softer vegetables (such as turnips and sweet potatoes) so that all of the vegetables finish cooking around the same time.
Notes
*Root Vegetables: parsnips, carrots, turnips, beets, sweet potatoes, other potatoes, leeks or other onion