Cut the pate` ingredients in small pieces and cook in butter covered on low heat, once well softened blend into a paste. Cut the beef in 4 equal parts and seal on a well preheated pan until well browned, remove from the beef and in the same pan using the butter cook the onions cut in thin strips for the sauce. Add the sugar and allow to caramelize. Add the red wine and reduce for 2 minutes before adding in the stock. Adjust the taste with the balsamic vinegar. Cut the potato in thick fingers boil and finish in some salted butter to add taste and colour. Sauté the vegetables and flavour with salt and pepper.