Peel, wash and cut the potatoes into pieces. Peel and wash the Jerusalem artichoke. Put 100 g aside, cut the rest into pieces. Peel and finely chop the onion. Heat butter in a pot.
Sauté the potatoes, pieces of Jerusalem artichoke and onion. Add stock and cook for about 15 minutes. Slice the rest of the Jerusalem Artichoke finely. Puree the soup with the cutting stick of the hand mixer. Whip cream until half stiff.
Stir half into the soup. Season soup with salt, pepper and lemon juice. Heat oil in a pan. Fry slices of Jerusalem artichoke for 1-2 minutes until golden brown. Wash the chives and cut into fine rolls.
Arrange the soup and 1 slice of Bündner Fleisch in plates, serve with the rest of the cream, Jerusalem artichoke chips and chives. Add the rest of the Bündner meat.