For the fried white sausage with mashed potatoes, first prepare the mashed potatoes. To do this, boil the mustard seeds in a small saucepan in a little salted water for about 20 minutes. Pour them into a sieve and rinse them after they have cooled down. Cut the bacon into small cubes, fry in a frying pan in oil over medium heat until crispy and drain on kitchen roll. Rinse the endive leaves, rub dry and cut into tender strips.
Wash the potatoes and boil them in salted water with the caraway seeds until soft. Peel them as hot as possible and press them through a potato ricer into a large enough bowl. Bring the milk to a boil and stir into the potato mixture (adjust the amount of milk!). Fold in mustard seeds, butter, endive strips and bacon cubes and season the mashed potatoes with salt, pepper and freshly grated nutmeg.
Cut the white sausages on both sides a few times and roast them in a frying pan in oil at low temperature on both sides for about eight minutes until golden brown. Drain on kitchen roll and serve with the mashed potatoes.