Clean, wash and drain the beans. Peel onions and finely dice 2 onions. Wash, peel and roughly grate the potatoes. Mix the potatoes, diced onions, 2 eggs, some salt, pepper and nutmeg well and put aside covered.
Wash pork fillets, dab dry, season with salt and pepper. Heat 2 tablespoons of oil in a frying pan and fry the fillets for about 5 minutes, turning them all round. Take them out and let them cool down a little.
Add stock and cream, stir in 1 1/2 tablespoons of mustard and sauce powder and bring to the boil again briefly. Season to taste with a little salt, pepper and lemon juice. Finely dice the remaining onion and fry briefly in 10 g fat.
Wash tarragon and parsley, dab dry and chop except for some tarragon for garnishing. Grind the toast bread in the universal chopper. Mix the toast, onions, chopped herbs, up to one tablespoon each, 1 egg, 2 tablespoons of mustard and a little salt and pepper.
Spread the mixture over the fillets, press well and place in an ovenproof dish. Pour the sauce. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 25 minutes. Meanwhile, cook the beans in little boiling salted water for about 20 minutes.
For the Rösti, heat a little oil in a large frying pan and add small, flat heaps with a tablespoon. Bake until golden brown, turning the pan. Keep the finished Rösti warm. Use the rest of the mixture to bake more Rösti until the mixture is used up (about 16 pieces).
Drain the beans and toss with 20 g fat and the remaining parsley. Arrange pork fillets with some sauce, beans and Rösti on a large plate. Serve sprinkled with a slice of lemon and remaining tarragon and garnished.