Peel, wash and chop the potatoes. Cook in boiling salted water for about 20 minutes. In the meantime clean, wash and cut the savoy cabbage into strips. Peel onions. Dice one onion, cut the rest of the onions into rings.
Wash the steaks and pat them dry. Cut the fat edge several times. Heat 1 tablespoon butter. Sauté the onion cubes in it. Add savoy cabbage, season with salt and pepper and fry for about 10 minutes. Deglaze with stock and whipped cream, finish cooking for another 5 minutes.
Season again. Drain potato water, add milk and 2 tablespoons of butter. Mash the potatoes, season with salt, pepper and nutmeg. Heat the oil. Fry the steaks for 2-3 minutes on each side at high heat.
Season with salt and pepper. Fry the onion rings in the frying fat until golden brown. Serve in portions garnished with herbs.