Place the puff pastry slices next to each other and let them thaw for about 30 minutes. Wash and clean the vegetables. Cut cauliflower into florets and asparagus into pieces. Cook cauliflower and carrots in 3/4 litre salt water for about 15 minutes, add asparagus and peas after about 7 minutes.
Drain the vegetables and collect the water. Wash and clean the mushrooms. Peel onion. Dice both and stew them in 10 g fat. Season with salt, pepper and nutmeg and let cool. Wash and chop parsley and mix it into the liver sausage.
Wash the meat, dab dry, fry in 10 g fat. Season with salt and pepper. Place the puff pastry slices on top of each other and roll out thinly. Cut out 4 squares (17 x 17 cm). Cut out mushrooms from the leftovers.
Put the steaks and mushroom mixture on the squares. Separate the egg. Brush the leaf dough corners with egg white, beat over the filling and press down well. Put the steaks on a cold rinsed baking tray. Bake in a preheated oven (electric: 225 ° C/ gas: level 4) for 15-20 minutes.
Place the puff pastry mushrooms on the baking tray about 5 minutes before the end of the baking time. Brush everything with egg yolk and finish baking. Heat the rest of the fat in a small pot and sauté the flour in it. Deglaze with 3/8 litres of vegetable water and milk and simmer for about 5 minutes.
Season with salt and pepper. Wash the chervil and, except for something to garnish, pluck and add. Heat the vegetables in it. Serve with the steaks. Garnish with chervil.