Peel the potatoes and cook them in salted water. Roast the onions in a large saucepan, then add the butter and flour and sweat until a golden yellow mass is formed.
Now deglaze with the broth and stir well, then bring to the boil to a thick sauce while stirring sporadically (add flour or water if necessary). Season with sweet and sour sugar and vinegar. Simmer gently and in the meantime boil the eggs hard, peel them and add them to the sauce.
Bring to the boil briefly and simmer on a low heat for four minutes. Serve immediately with the potatoes.