How to make
Dilute the flour in the yoghurt and add salt and cumin to taste. Put it in a pot, add the water and wait for it to come to a boil, stirring constantly.
Remove it from the heat and put 1 tablespoon of butter in. Stir and thicken with the egg yolks that have been whipped with a little vinegar, temper it carefully. Serve with croutons.
Optionally, you can add crushed garlic.