In Congress Poland, where Rosa grew up, the main meal of the day is obiad, taken in the middle of the afternoon. It begins with a zupa (a soup that alone sustains modest families), followed by a danie (a single dish of grain, vegetable, or poultry). Kiszonki (lacto-fermented vegetables) accompany everything, stored in the cellar, and słodkości (sweet treats with poppy seed or farmer cheese) close festive days. Among the Jews of Zamość, the same structure adapts to the rhythm of Shabbat.

The acidic heart of this cuisine is lacto-fermentation: a rye sourdough (zakwas) that sours soups, and brine that transforms cucumbers and cabbages. It is a poor person's technique—it preserves without sugar or meat, lasts through winter, and gives that sour-fresh taste that marks the entire table of Central Europe.