1. Cut white bread in course cubes. Put one hand full aside. Put the rest in a big bowl cover with milk and let it rest for about 20 minutes.
2. Cut the onions into fine cubes, chop garlic. Sauté with oil in a pan for 2 minutes at middle heat, chop spinach leaves coarsely and add them.
3. Shred parmesan and fold into the bread milk mass together with flour and spinach. Season with nutmeg, salt and pepper and stir with the eggs as well as with the rest of the bread cubes. Let rest for another 15 minutes.
4. Roll out 2 long stripes of plastic wrap on the work space so they overlap in the middle. Place the mass in the middle and form it to a 10cm thick roll with help of the plastic wrap. Knot the ends of the foil to close both ends. Put two layers of aluminum foil around and screw in the ends.
5. Cook the roll in slightly simmering water for about 30 minutes. Turn the roll from time to time. Reduce temperature and let steep for another 30 minutes. Take dumplings out of the water and let cool down.
6. For the jus, sauté tomato puree in a small pot for 1 minute. Deglaze with red wine, stir in balsamic and sugar. Season with salt and pepper and let reduce for 10-15 minutes until it gets slightly thick. Stir in cold butter and put aside.
7. Peel the onion and cut into slices. Sauté with butter in a pan at middle heat. Reduce heat and steam for 10 minutes until the onions are soft and golden brown. Stir in maple syrup and roast for another 2 minutes.
8. Preheat a water bath with the Sous Vide Stick to 52°C for the beef filet. Dab dry the filet and vacuum in a vacuum bag. Cook for about 90 minutes in the water bath.
9. Cut the dumpling into slices as thick as a finger. Grease from both sides with oil and brown in a pan. Heat Kühne Red Cabbage Original in a pot.
10. Heat iron pan until it smokes. Dab dry the beef filet rub with oil and sear from both sides for about 1 minute. Take filet out of the pan, let rest for 2-3 minutes and cut into thin tranches.
11. Grease one side per dumpling with red wine jus. Top half of the slices with rocket, Kühne Red Cabbage Original and filet slices. Season with salt and pepper. Drizzle one extra tbsp of juice on the beef and spread the onions on it. Top with a dumpling slice.