1. Heat the butter in a large, heavy-based saucepan until foaming. Add the orange peel and vegetables.
2. Stir-fry for 2-5 minutes, then cover and cook very gently over low heat until all the vegetables are soft; 15-30 minutes, depending on size of chunks. Stir with a wooden spoon from time to time. Season with a little salt, pepper and nutmeg.
3. Sprinkle with cornflour, if necessary, and stir thoroughly.
4. Gradually add first the chicken stock and then the milk, stirring constantly. Continue cooking, stirring, until the soup comes to the boil.
5. Remove the saucepan from the stove, transfer the soup to a food processor or blender and purée (blend/process) until smooth.
6. If serving the soup hot, return it to the saucepan and reheat over low heat to heat through.
7. Stir in the cream and serve in heated soup bowls.
8. If serving the soup chilled, refrigerate it for 2-3 hours after step 5, then stir in the cream and serve the soup in chilled soup bowls.
For a more luxuriously flavoured soup, add 1-2 sliced leeks, 1-2 sliced parsnips, a few fresh celery leaves and 30 ml (2 tbsp) freshly grated ginger when sautéeing the vegetables. Use 60 ml (4 tbsp) arborio rice instead of potatoes. Sprinkle with finely chopped coriander before serving.
Alternatively, use 60 ml (4 tbsp) cooked tapioca instead of potatoes or arborio rice. Add 125 ml (1/2 cup) whipped cream at the end and sprinkle with 30 ml (2 tbsp) crisped almonds.
For a savoury finish, sprinkle the completed soup with 15-30 ml (1-2 tbsp) grated Parmesan cheese as well as a few croûtons fried in butter to which a very small quantity of chilli paste has been added.