Heat the sunflower oil in a large saucepan over a medium heat.
Add the onion and cook for 10 minutes, stirring often, until soft.
Add the ginger, garlic, chilli and coriander, stir well and cook for a further minute or two.
Add the diced vegetables. The Jerusalem artichokes take a bit longer to cook than the celeriac so I suggest chopping them a bit smaller. Stir to coat in the spice mix then pour in the coconut milk and the vegetable stock.
Bring to the boil then reduce to a simmer and cover. Cook for 20-30 minutes or until the vegetables are soft.
Blend until smooth. I find that a handheld blender is the most convenient way to do this. Season to taste with salt and pepper.
Season with salt and pepper to taste and serve with freshly chopped coriander and some extra chilli sauce if liked.