All the quantities are approximate so you can use everything to your own taste
2 onions, cut in quarters
2 heads of garlic (in summer I use green garlic heads), cut in quarters
celery root
2 sweet potatoes
3 carrots
any other root vegetables
some black pepper, I normally ground it fresh
some thyme or rosemary
coarse sea salt
2-3 tbl spoons of extra virgin olive oil
Peel and cut your root vegetables up to your liking add the rest and mix up a bit, you actually do not need a lot of oil just a bit and then just mix trying to coat everything slightly in it. Put all that to the roasting tray, set your oven to 170⁰C and check after 30 minutes and then from time to time until it is ready to your liking. It goes well with any meat and on its own.