Trim, prepare and wash the cabbage, cut lengthwise into quarters, take out the hard core and largest ribs, rinse and drain well.

Cut the leaves into very thin strips and place in a large pot with the stock, the herbs and 5 black peppercorns.

Trim and wash the leek; slice it into rings; peel the potato and cut into small pieces; add both to the soup with 1/2 tsp salt, cover, bring to the boil and simmer for 50 minutes.

Remove the skin of the sausage (a highly flavoured and rather fatty sausage made with plenty of paprika is best) and dice.

Heat a non-stick frying pan and when it is very hot, fry the sausage for 2-3 minutes, turning the pieces with a non-stick spatula.

The sausage should be crisp; drain off and discard all the fat it has released and leave the pieces to finish draining on kitchen paper.

When the cabbage is very tender, use a hand-held electric beater to reduce the soup to a creamy consistency or allow to cool a little and process in batches in the blender, then return to the saucepan and reheat to just below boiling point.

Draw aside from the heat; add salt to taste, stir in the cheese, cream, parsley and sausage. Sprinkle with croutons and serve.