2 Briefly sauté the potatoes in butter, together with the soup vegetables and bouquet of herbs. Add a little salt and pour in the stock. Half cover and allow to simmer for 30-40 mins. on a low heat .
3 Remove the soup vegetables and the bouquet of herbs. Stir the soup well with a large whisk. Season with salt and nutmeg. Mix the chervil and the cream and add to the soup. Simmer until creamy on a low heat..
4 Shortly before serving, season the soup with vinegar. Cut the Emmentaler into thin slices.
5 To serve: put the slices of Emmentaler on plates and pour the hot soup on top of the cheese.