Place all the ingredients, except for the pepper and oil, into a large pan or stockpot.
Bring to the boil, then cover, and reduce the heat to a gentle simmer.
Cook for 20 minutes, or until the pumpkin is soft.
Blend until smooth.
Add the oil and the pepper, then blend again for a few seconds, to make sure the oil doesn't separate.
Serve immediately, or keep in the ‘fridge for up to a week, stored in an airtight container. This soup freezes well, and can be kept for up to three months in the freezer.