Peel and wash the potatoes. Bring to the boil in salted water and cook for about 20 minutes. Peel and finely chop the onion. Melt 1 tablespoon of fat in a saucepan. Fry the onion in it. Add beans and 100 ml water, bring to the boil and cook over medium heat for about 7 minutes.
Boil the eggs in boiling water for about 8 minutes until they are waxy, then rinse and peel them. Fry flour in a pan without fat until golden brown. Add 2 tablespoons of fat and mix. Deglaze with 1/2 litre cold water while stirring and let simmer for 5 minutes.
Season to taste with salt, pepper, vinegar and sugar. Add the eggs to the sauce and warm them up. Drain and mash the potatoes. Stir in 1 tablespoon of fat and milk. Season to taste with salt and nutmeg.
Wash the parsley and chop finely, except for something to garnish. Serve eggs in sauce, beans and mashed potatoes together. Sprinkle with parsley and garnish.