For the gratin, peel and wash the potatoes and cut or slice them into thin slices. Layer potato slices fan-shaped in a gratin dish (approx. 24 cm Ø). Mix 150 g cream and milk. Season with salt and pepper and pour over the potatoes. Bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for approx. 45 minutes.
For the beans, cook frozen beans in boiling salted water for 10-12 minutes. Pour off, rinse with cold water and drain. Heat 1 tablespoon of oil in a frying pan. Fry the bacon until crispy. Take out, drain on kitchen paper. Set the pan with bacon fat aside.
For the steaks, wash the meat, pat dry and cut into 4 medallions (3-4 cm high). Tie the steaks into shape with kitchen twine. Add 1 tablespoon of oil to the bacon fat in the pan and heat it strongly. Fry the steaks for 3-4 minutes on each side (see tip). Season with salt and pepper, wrap in aluminium foil and leave to rest for about 10 minutes.
For the sauce, peel and finely dice the shallots. Steam half of the shallots in hot frying fat until translucent and deglaze with white wine, 100 ml water and 100 g cream. Bring to the boil and simmer for about 2 minutes. Beat the truffle butter in pieces (do not boil any more!). Season sauce with salt, pepper and 1 pinch of sugar.
Wash parsley, shake dry and chop. Heat butter in a pan. Sauté the remaining shallots in it. Swivel the beans in it and heat them up. Finally crumble bacon over it. Season with pepper. Serve with fillet steaks, gratin and truffle cream. Sprinkle with parsley.
TIP - Perfect steak: First fry the meat on each side for about 1 minute. Switch down to medium heat. Then fry on each side for a pink steak (medium) for 2-3 minutes and fry on each side for a well done steak for about 1 minute longer.