Soak bread in water. Peel and finely chop the onion. Squeeze the bread. Knead minced meat, bread, onion, egg, salt and mustard in a bowl. Form 8 flat meatballs from the mince mixture. Wrap a slice of bacon around each edge.
Heat the oil in a large pan and fry the meatballs for 3-4 minutes on each side. In the meantime, crush pepper coarsely in a mortar. Turn the bacon edges of the meatballs briefly in the hot oil. Remove from the pan and keep covered and warm.
Put butter into the pan, melt, deglaze with cognac, cream and stock, bring to the boil, simmer for about 2 minutes. Stir in the sauce thickener and let it simmer for about 1 minute while stirring. Season to taste with salt and sugar.
Arrange 1 meatball and some sauce sprinkled with crushed pepper on each plate. Garnish with thyme as desired. Add the remaining meatballs and sauce.