The soup that they ate in Pride and Prejudice was "White Soup".
White Soup which originated in the 17th century France, became a popular food, for serving at balls in Jane Austen's time.
The White Soup dish is also referenced in Pride and Prejudice by Mr. Bingley, as Mr. Bingley plans the Netherfield Ball.
In Pride and Prejudice, "white soup" is a creamy, rich, and expensive dish made from a veal or chicken stock, thickened with almonds, rice, and/or stale bread, and finished with cream and egg yolks.
The white soup was a traditional, elegant dish served at balls and formal dinners in the Regency era, named for its smooth, white appearance rather than a lack of dark meat.
Food mentioned in Jane Austen's Pride and Prejudice reflects the dining customs of the Georgian era, including elegant dishes like white soup served at balls, luxurious items such as pigeon pie, poached salmon, and iced creams at wealthy households, and simple fare like pea soup or fruit at others.
Food is also often used to signify social status and can indicate a family's wealth, like the fine fruits at Pemberley.