To cook the tongue, roughly chop the soup vegetables, do not peel and quarter the onion. Put the tongue in a large saucepan and pour in enough water to cover everything. Bring to the boil and skim off the foam that forms when boiling.
Add the soup vegetables and the spices and let everything simmer gently for about 2 hours. Then skin. Tip: If you prick the tip of the tongue and it`s soft, the rest of the tongue is soft too.
For the mustard sauce, dice the shallots and sauté in the butter. Dust with flour and let brown a little. Deglaze with cream and enough tongue stock until the desired consistency is achieved. Let everything simmer for another 5 minutes.
Then take it off the stove and stir in the mustard. Season again with salt, pepper and a pinch of sugar. Serve with the tongue sliced open.