Peel the onions. Cut 1 onion into quarters, cut the remaining onions into thin rings and set aside. Peel carrot and celery and cut roughly into pieces. Bring 1-1 1/2 litres of water, onion quarter, carrot, celery, bay leaf and peppercorns to the boil in a pot. Cover and simmer for about 5 minutes. Wash the smoked pork, dab dry and put into the stock. Cover and simmer at low heat for about 40 minutes.
Peel, wash and chop the potatoes. Pears peel, halve, core and likewise cut into cubes. Cover the potatoes and pears and cook them for 15-20 minutes in little boiling salted water
Wash the chives, shake dry and cut into small rolls. Mix sour cream, horseradish and 2-3 tablespoons of milk. Season to taste with salt and pepper
Heat 100 ml milk and 30 g butter. Drain potato and pear mixture, add hot milk and mash everything coarsely. Season puree with salt and pepper. Put onion rings in a bowl, dust with flour and toss. Heat 20 g butter in a frying pan, fry the onion rings until crispy brown, turning them over. Remove the smoked pork from the stock, drain and cut into thin slices. Arrange the smoked pork together with the pear and mashed potatoes on plates. Spread roasted onions on the puree and put some horseradish cream on the slices of Kasseler. Sprinkle with chives. Add the rest of the sour cream