- Place vegetable stock into a saucepan and bring to the boil. Cut, peel and seed butternut pumpkin and add to stock. Cover saucepan, reduce heat and simmer for 15 minutes until pumpkin is tender. Remove 1 cup of pumpkin mixture. Mash and cool.
- Meanwhile heat olive oil in a small pan and add onion, garlic clove, ginger, cumin, coriander and dried chilli flakes. Cook for 5 minutes until onion is soft. Remove from heat.
- Stir onion mixture into saucepan with remaining cooked pumpkin. Puree mixture with a stick blender (or transfer mixture to a blender to process) until smooth
- Add 1 1/2 cups water and return to the boil. Ladle spiced pumpkin soup into warm bowls, top with a dollop of sour cream and fresh coriander. Serve.