Mix the beef with the egg, the mustard, half of the breadcrumbs and the cheese and pepper and salt to taste and make 4 balls. Roll them through the remaining breadcrumbs. Fry them in the butter until brown on all sides. Add 1/2 cup of water, close the lid and simmer for 20 minutes.

Stir fry the onion, the bacon and the mushrooms for 5 minutes; add the breadcrumbs, the egg, the lemon rind and pepper and salt to taste. Put a spoonful of this mixture on each meat slice and roll these up. Tie them up with a piece of rope. Roll them through the flour and fry the rolls brown on all sides in butter. Add 2 cups of water and bring to the boil. Simmer for half an hour. Add the mustard and garlic and simmer half an hour more.