Peel and wash the potatoes and Jerusalem artichokes. Coarsely dice both, except for 50 g Jerusalem artichoke. Peel and chop the onion
Heat the butter in a pot. Fry the potatoes, pieces of Jerusalem artichoke and onion. Pour a good 3/4 l of water and bring to the boil. Stir in stock. Cover and simmer for about 10 minutes
Cut the rest of the Jerusalem artichoke into fine slices. Fry in hot oil for about 2 minutes until golden brown. Drain
Puree the soup. Whip cream until half stiff. Stir half into the soup. Season to taste with salt, pepper and lemon. Serve the soup with Bündner meat, the rest of the cream and Jerusalem artichokes. Wash the chives, chop finely and sprinkle over the soup.