Chop all roots small and similar size. (about 1/2 to 1 inch). Ratios of ingredients are up to you - what you like best.
Toss in a bowl with seasoning and olive oil. The amount depends on how many vegetables you're using. Usually about 2 Tbls. Spread onto a foil lined baking sheet (for a quick clean up). Make sure they have some room. Don't pile them on top of each other. Allow space between pieces works best to get all sides roasted. Otherwise, they just create steam and cook, but don't roast.
Roast for 40-60 minutes on 400. If I have a large batch (two baking sheets worth), I turn the broiler on low for the last 5 minutes if the outsides have not yet got toasty.
Make these in advance, then before serving, toss back onto a baking sheet under the LO broiler for 10 minutes. That will crisp them up and heat them through. Serve with sprigs of fresh rosemary on top. Lovely!