Wash the parsley, shake dry and chop the leaves finely. Cut bread into cubes of about 1 cm. Peel and finely chop the onion. Melt the fat. Sauté the onion in it. Add milk and parsley, season with salt and pepper. Stir in eggs and pour everything over the rolls. Mix and let it swell for about 10 minutes. Form the roll mixture on a damp tea towel into a roll (approx. 5 cm Ø). Roll up and tie up the ends of the cloth with thread. Cook for approx. 45 minutes in an appropriately large pot in plenty of slightly boiling salted water, turning occasionally.
Peel and halve the red onions and cut into strips. Heat 1 tablespoon of oil in a saucepan. Sauté the onions for about 5 minutes, add sugar and caramelise. Deglaze with 200 ml red wine and vinegar and simmer covered for 15-20 minutes
Wash the asparagus and cut off the woody ends. Halve the asparagus spears. Clean and trim the mushrooms and, depending on their size, possibly halve them. Cook the asparagus in salted water for about 5 minutes until al dente. Drain and rinse under cold water
Take the napkin dumplings out of the water and wrap them in the cloth. Cut the roll into about 12 slices. Heat 2 tablespoons of oil in a large frying pan and fry the napkin dumplings for 3-4 minutes, turning them in portions. Remove and keep warm. Heat 2 tbsp. oil in a frying pan and fry the mushrooms and asparagus for approx. 5 minutes.
In the meantime, pat the meat dry and season with salt and pepper. Heat 1 tablespoon of oil in a large frying pan. Fry the meat for 6-7 minutes, turning it over. Remove meat and keep warm. Deglaze the meat with 50 ml red wine and bring to the boil. Pour the gravy with the red wine onions
Mix starch and 1 tablespoon cold water. Pour into the onions, bring to the boil again and simmer for about 1 minute. Season to taste with salt, pepper and a little sugar. Arrange meat, vegetables, dumplings and red wine onions on plates and serve immediately