Peel, wash and chop the potatoes. Cook in salted water for about 20 minutes
Clean the mushrooms, wash if necessary and cut into slices. Peel and chop the onions. Fry them in 1 tbsp. hot oil until crispy, take them out. Fry the mushrooms in frying fat until golden brown. Season with salt and pepper, take out
Dab the steaks dry and cut the fat edge several times. Heat 1 tablespoon of oil in the frying fat. Fry the steaks for 3-4 minutes on each side. Season with salt and pepper. Keep warm
Heat milk and butter. Drain and coarsely mash the potatoes, stir in the milk. Fold in mushrooms and fried onions. Season to taste with salt and nutmeg
Cut the herb butter into slices. Serve the puree and steaks with the herb butter. Garnish with parsley