A recipe from grandmother's more thrifty times; rarely encountered today.
Melt the butter, and whisk in flour. Add meat broth or water. Add the rinsed and chopped herbs, and briefly bring to a boil. Let soup cool a bit, then thicken with egg yolk. Season with salt, pepper, and a pinch of sugar. Stir in sour cream when serving.
In some Swabian kitchens, very finely chopped garlic gets scattered on top of the soup.
From: D'SCHWAEBISCH' KUCHE' by Aegidius Kolb and Leonhard Lidel, Allgaeuer Zeitungsverlag, Kempten. 1976. (Translation/Conversion: Karin Brewer) Posted by: Karin Brewer, Cooking Echo, 8/92