Peel, wash and quarter the potatoes. Cook in boiling salted water for about 20 minutes. Wash the meat, dab dry and cut into strips. Peel and chop onion. Clean, clean and slice the mushrooms.
Clean and wash spring onions and cut them diagonally into rings. Heat the oil in a pan. Fry the meat for approx. 3 minutes, turning it over. Add onion and mushrooms and fry for about 4 minutes, season with salt and pepper.
Dust with flour, sweat it on. Deglaze with cream and bouillon. Stir in mustard and spring onions, except for something to sprinkle, and simmer for 2-3 minutes. Drain potato water. Add milk and butter to the potatoes and mash to puree.
Wash the herbs and dab dry. Pluck parsley leaves from the stalks and chop them. Cut chives into fine rings. Fold the herbs into the puree and season with salt, pepper and a little nutmeg.
Arrange everything and sprinkle with the rest of the spring onions.