Crush mustard seeds, sea salt, peppercorns and thyme in a mortar. Mix with 2 tablespoons of oil. Dab meat dry. Heat 2 tablespoons of oil in a frying pan and fry the meat all around. Place on the fat pan of the oven and rub with the mustard mixture.
Cook in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 40-45 minutes. (It is best to measure with a roast thermometer: the meat should have 58-60 °C at the core).
Cut the cheese into 16 cubes. Wash parsley, shake dry. Pluck off leaves and chop finely. Knead potato dough with parsley. Form 16 thalers from the mixture, place one cheese cube in the middle of each and seal the dough around it.
Turn thalers in breadcrumbs. Wash and clean the beans. Put the beans into little boiling salted water and stew covered for 15-20 minutes. Coarsely chop the walnuts.
Remove the meat from the oven, cover with aluminium foil and let it rest for about 10 minutes. Collect the broth and keep warm. Heat 2 tablespoons of oil in a large frying pan. Fry the potato and cheese taler in it while turning for about 5 minutes.
Roast the nuts in a pan, sprinkle with sugar and allow to caramelize. Drain the beans and let them drain. Add butter and beans to the nuts and season with salt and pepper. Cut the meat open.
Serve with potato thalers and beans, sprinkle with broth.