Peel and cut the root vegetables into similar sizes. Put the root vegetables in an ovenproof dish with vegetable oil, salt and pepper. Bake the root vegetables in the oven with the lamb roll on 350 Fahrenheit (175 Celsius).
Take the vegetables out of the oven when they are soft, and cover the ovenproof dish with aluminum foil. Re-heat them for 10 min on 400 Fahrenheit (200 Celsius) before serving.