This is a Jamie Oliver type way of doing roast veges.
Take any veges suitable for roasting ...potatoes, sweet potatoes, pumpkin, carrots, parsnip etc. Chop into smallish sized pieces, cook in salted water until cooked. Heat some oil in a roasting pan in the oven. Drain veges and leave to steam dry for a minute or so. Give them a bit of a shake in the pot to roughen up the edges (this makes them nice and crispy when they are cooked) Toss into the hot oil and sprinkle with plenty of fresh rosemary. You can add oinion cut in quarters at this stage too. Bake at 200C for about an hour, turning them a few times.