Peel and dice 1 onion, garlic, celeriac, turnip, carrots and potatoes.
Sweat the onions and garlic in a large saucepan. Add celeriac, turnip, carrots, potatoes and fill up with enough vegetable stock to cover all the ingredients. Cover the pot and simmer for 20-25 minutes.
Meanwhile, peel the second onion and cut into fine slices. Fry in oil until dark brown. Season with a little salt and pepper.
Then pour off the liquid from the pan, but collect it. Use the blender to puree all the ingredients in the pot and gradually pour in the liquid that has been collected until the puree has the desired consistency.
Season with salt, pepper and nutmeg and sprinkle with the onions on top.