Heat the oil in a large saucepan, add the onion and cook for 5 minutes until softened. Add the ginger, ground coriander, lemon grass, orange peel and squash. Pour in the stock and coconut milk and bring to the boil. Leave to simmer for 12–15 minutes until the squash is soft.
Remove the lemon grass and orange peel and use a stick blender to whizz to a smooth paste. Season to taste and divide between serving bowls. Sprinkle over the chilli and fresh coriander to serve.