Winter’s root vegetables need help if they are to be interesting. Most are starchy and need butter, oil or cream to be palatable. They do respond well to spices and curry powder, though.
Peel the vegetables and cut them into 3cm dice. Keep them in separate piles.
Heat the olive oil in a wok and add the vegetables in the right order, depending on the time they take to cook - the hardest first and softest last, so it will be the swedes first, then after 5 minutes the carrots and celeriac, and then after another 5 minutes the parsnip cubes.