My grandfather loved it because it was reliably followed by a cake or by sweet yeast dumplings with a divine salty crust. My mother continued the tradition and we all loved it.
I am the one who changed it for just potato soup accompanied by baguette, some olives, a bit of pizza or what else the kitchen offers. The quick and easy way!

Potato cucumber soup

4 tbs olive oil
4-5 spring onions, chopped
about 750g potatoes, diced
1 large fresh cucumber, peeled, seeded and chopped
1 ts salt
a pinch of freshly ground black pepper
about 1l  vegetable stock ( I use vegetable stock powder from the wholefood store)

Heat the oil in a saucepan and cook the spring onions and the potatoes over low heat, stirring, until the vegetables soften and begin to turn golden. This step is very important, because it gives a special flavour to the soup. Much better than the raw vegetables simply thrown into the stock.
Add salt and pepper.
Pour in the stock. Should cover the vegetables by about 3 cm.

Simmer for about 10 minutes.

Add now the cucumber and let it simmer for only 5 minutes more. (No longer!)
Liquidize it in a food processor until smooth.
You can pimp the soup with a bit of sour cream, freshly chopped parsley, croutons….

And of course, have a piece of cake afterwards if you like to follow the old traditions!