Potato celeriac and ginger soup

Heat butter in soup pot over medium heat. Add onions and sauté for 2 minutes or until softened. Add potatoes, celeriac and Ginger and sauté for 2 more minutes, or until vegetables are coated in butter. Add stock and bring to a boil. Reduce heat and simmer for 20 minutes, or until vegetables are very soft. Puree with a hand blender or in a food processor until smooth. Add cream and simmer for 5 minutes to combine flavours. Season with salt and pepper to taste. Serve topped with pickled Ginger.