A hair in Rosa's egg-drop soup
Rosa certainly did not approve of Ilse's relationship with her son. She thought Ilse was trouble.
Rosa even suspected that Ilse's true motive was the prestige to some Lutherans in marrying a Jewish merchant, though this made little sense considering Ilse's family aristocratic background.
But Ilse was never easy to deal with, and not only for Rosa. Family relations would forever afterwards remain prickly. The two women never did get on and Gerhard's choice of wife would always make life difficult from then on for every member of the family.
Ilse particularly delighted in telling the story of how, when Gerhard and Ilse first met. Rosa regularly managed to turn up at the places where they were dining out, but she would never agree to join them at the table.
In any case, Rosa herself always avoided Chinese restaurants, being wary about the hygiene standards in the kitchen.
Eventually Gerhard and Ilse persuaded Rosa to join them for a meal, and where did they take her but a Chinese restaurant? Rosa had joked beforehand that she hoped she would not find a Chinese hair in her soup, and of course that is exactly what she did find—a thick, black hair in her egg drop soup.
Ilse in old age found this hugely amusing.