Melt the butter in a large, lidded saucepan. Add the prepared vegetables and cook for 5 minutes.
Add the stock and season to taste. Bring to the boil, cover and then simmer for 25 minutes or until the vegetables are tender.
Transfer to a blender or food processor and purée until smooth, in batches if necessary.
Return the soup to the pan, add the milk and reheat gently. Serve with freshly ground pepper and parsley.
Suggestion: Serve with wheaten bread or with Naan or bread sticks as a change.