Wash the potatoes and cook in boiling salted water for 15-20 minutes. In the meantime, peel and wash the carrots, cut them in half lengthwise and cut them into pieces. Clean and wash spring onions and cut into rings. Cook carrots in little boiling salted water for about 5 minutes, drain. Drain potatoes, rinse, peel and cut into six lengthways.
Peel garlic and chop finely. Press the steaks flat on the work surface by hand and cut them into 3/4 pieces with a knife. Open the meat to make the butterfly shape. Season with salt, pepper and lemon peel. Heat oil in a pan and fry steaks on each side for about 7 minutes. Keep warm. Stir sour cream and mustard until smooth. Fry the potatoes in frying fat until crispy. Shortly before the end of the cooking time, add carrots and spring onions and fry. Wash the sage and pluck the leaves from the stems.
Stir sour cream and mustard until smooth. Fry the potatoes in frying fat until crispy. Shortly before the end of the cooking time, add carrots and spring onions and fry. Wash the sage and pluck the leaves from the stems. Season vegetables with salt, pepper and sage. Add meat to the vegetables and fry again briefly. Arrange on 4 plates and add the cream mustard sauce