Peel onions, cut one of them into fine cubes. Clean, clean and chop the mushrooms. Cut the bacon into fine cubes. Leave the bacon in a pan without fat until crispy.
Add onions and mushrooms and fry for about 6 minutes. Season with salt and pepper. Wash the meat and dab dry. Heat 1 tablespoon of oil in a frying pan. Fry the meat on all sides for 10-15 minutes at medium heat.
Knead minced meat, liver sausage, 2 tablespoons mustard, egg and mushroom mixture. Roll out the puff pastry and temper briefly at room temperature. Spread the filling evenly over the dough, leaving a rim of approx. 4 cm free.
Spread the edges of the dough thinly with water. Whip the meat into the dough. Press the edges of the dough well. Cut off excess dough and cut into strips with a dough wheel. Garnish the dough with it.
Whisk the egg yolk and 3 tbsp. milk and spread the dough with it. Place the cured pork on a baking tray lined with baking paper and cook in a preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 35 minutes.
In the meantime, clean the savoy cabbage, cut in half and remove the stalk. Cut the savoy cabbage into pieces. Dice the remaining onion. Heat butter in a pot. Sauté diced onion until transparent. Add the savoy cabbage and stock and stew for about 15 minutes in a closed saucepan.
Season to taste with salt and pepper. Cut the smoked pork loin into slices and arrange on plates with the savoy cabbage. Serve with a mustard-honey sour cream.