Sauté the shallots in the oil, add the potatoes and black salsify, fill up the vegetable stock and cook until soft. Pour on the cream, simmer a little more, puree and strain through a sieve.
Bring to the boil again and season to taste.
Fry the chanterelles in a pan, season with salt, pepper, chilli flakes and vanilla. Serve the soup with the chanterelles.