Sort the kale, wash thoroughly several times and drain. Pour into 1/2 litre of boiling water and allow to collapse. Drain and chop roughly. Peel onions and cut into slices except for one.
Heat 20 g clarified butter in a pot. Brown the onions slightly and add the kale. Wash the smoked pork loin and ham bones, add to the kale and pour on 1/4-3/8 litres of water. Cover and cook for about 1 hour.
In the meantime, wash the potatoes and cook them in plenty of boiling water for about 15 minutes. Finely dice the remaining onion. Heat the fat in a pot, sauté the onion in it until transparent, add flour and sauté.
Deglaze with stock and milk while stirring, bring to the boil and simmer for 2-3 minutes. Stir in mustard and season to taste with salt. Keep warm. Drain potatoes, rinse cold and peel.
Let it cool down. 15 minutes before the end of the cooking time add Mettenden to the curly kale and cook at the same time. Heat the remaining clarified butter in a pan and fry the potatoes all around. Sprinkle with sugar and season with a little salt and fry for 1-2 minutes more.
Remove the ham bones from the kale and season the kale with salt if necessary. Remove the smoked pork loin from the bone and cut into slices. Put the kale on a plate, arrange the smoked pork loin and cooked sausages on top.
Sweet roast potatoes and mustard sauce extra.