Remove the roots and stalky ends from the coriander. Wash the leaves and dry in a salad spinner or paper towel before roughly chopping. Wash the roots and stalks well to remove any dirt clinging to the roots. Shake off any water and finely chop.
Heat the oil in a large saucepan over medium-high heat before adding the onion and garlic. Cook until the onion becomes translucent.
Add the ginger, lemongrass and coriander roots and stalks. Cook until the stalks become soft before adding the pumpkin.
Toss the pumpkin in the oil and cook for 5 minutes. Add the vegetable stock and bring to a boil before reducing the heat to lower. Cook for 30 minutes or until the pumpkin is tender. Remove from heat and allow to cool slightly.
Pour the soup into a blender and blend until smooth. Add most of the chopped coriander (cilantro) leaves reserving some to garnish the soup. Blend until the soup is speckled with flecks of green.
Return to a clean saucepan and add the coconut milk. I like to only add half the milk, reserving the rest for garnish. Serve with shaved coconut, the remaining coriander (cilantro) leaves and chilli.
I like to use butternut pumpkin (butternut squash to my Northern Hemisphere readers) but feel free to use whatever pumpkin you prefer.