1. Heat the oil in a large saucepan over low heat. Add the grated ginger, sliced shallots and garlic and lightly fry, stirring continuously. Cook until the shallots are soft.
2. Add the butter and allow to melt before stirring in the celeriac and herbs. Pour over a generous gulp of the chicken stock and sweat the vegetables for 5 minutes, before adding the remaining stock. (Sweat the vegetables by adding a small amount of stock to prevent burning and seal with the lid of the saucepan to create as much steam and pressure as possible – this helps in tenderising the veg and releasing flavour)
3. Pour over the remaining stock and simmer with the lid on for 30 minutes, or until the celeriac is tender. Remove from the heat and allow to cool.
4. Pour in the cream and blend until smooth.
5. Season with salt and pepper to taste and serve with a teaspoon of fresh cream and a sprig of coriander.