Melt the butter in a heavy saucepan. When it foams, add the potatoes and onions and turn them in the butter until well coated. Sprinkle with salt and freshly ground pepper. Cover and sweat on a gentle heat for 10 minutes. Add the stock and boil until the potatoes are soft, then add the cabbage and cook with the lid off until the cabbage is cooked. Keep the lid off to retain the green colour. Do not overcook or the vegetables will lose both their fresh flavour and colour. Purée the soup in a liquidizer or blender, taste and adjust seasoning. Add the cream or creamy milk before serving.
If this soup is to be reheated, just bring it to the boil and serve. Prolonged boiling spoils the colour and flavour of green soups.
© 2001 Darina Allen. All rights reserved.