Onions peel and quarter 1 1/2 onions. Clean, wash and cut the soup greens into large pieces. Wash the knuckles. Put quartered onions, 3 bay leaves, soup greens, salt, pepper and knuckles in a large pot.
Bring to the boil covered with water and simmer at medium heat for about 1 hour. Lift the knuckles out of the stock. Pour stock through a sieve and measure 1/2 litre. Put the knuckles on a fat pan of the oven.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 1 3/4 hours. Gradually add the measured stock and braising stock. In the meantime, finely dice 1 1/2 onions.
Heat the lard in a pot. Add the onions, 3 bay leaves, juniper and caraway seeds and fry briefly. Add sauerkraut. Deglaze with broth, season with salt, pepper and sugar and braise for about 40 minutes.
Arrange the sauerkraut and pork knuckles on a plate. Boiled potatoes and mustard taste good with it.