This is a very interesting recipe from Balthasar Staindl’s cookbook. His name for it translates as ‘dust soup’:
Staub soup
cclxvii) Take three egg yolks to a table (auff ain tisch). Salt them and beat them well. Then take the staub. First boil it up (woel in am ersten), let it cool, and then pour it in with the egg yolks. Boil it like wine soup. If the staub is quite sour, pour on some water. If it is too sour for women in childbed, boil a spoonful of sugar in it. You also use cream in place of the eggs. That is also not bad. It clears out the stomach.
How to prepare the staub at the start
cclxviii) Take wheat bran (Waitzen kleyben), nicely stirred with water (schoen kleyben angeruert), mix it, and stir in a little sourdough leaven (urhab). Thus make a starter (dümpffel) with the above-mentioned bran. Let it stand over night and it will turn sour. When it has turned properly sour, pour fresh water in with it and stir it often, that ways it turns sour. The bran must not be too spare (oed), but must be mealy (ain melbige). From this staub, you prepare staubsuppen as is described above.
When I read the title, I was nonplussed. Staub means dust in modern German, and meant much the same thing then, but the second part makes it clear what the recipe is all about and suggests where its name may come from. The dish belong to a family of sourdough soups that are still customary across North Central Europe, known as zurek in Polish and kyselo in Czech. German cookbooks often call the modern version Schlesische Saure Suppe.
Modern versions tend to include meat, mushrooms, and other vegetables, and it is possible that these were already included in the sixteenth century. Staindl’s chapter on soups – and yes, there is an entire one and I will post the recipes – tends towards the purist, though, and that makes sense when you think of soup as one course of several. Thus here, we get only sourdough soup.
The process is involved, but manageable. Wheat bran – ideally including a fair bit of flour still stuck to it – is mixed with sourdough, allowed to rise, then stirred into water and the liquid drained. This liquid – confusingly named staub, presumably after the flour bust stuck to the bran – then becomes the base for a soup bound with egg or enriched with cream. This would normally be served with bread and butter either as part of a large meal or as a small one by itself.
I find it hard to imagine what this would taste like, but it sounds worth trying out when I can get my hands on some fresh sourdough. Alternatively, while this is not normally sold in Germany, soup manufacturer Knorr actually makes an instant version.
Balthasar Staindl’s 1547 Kuenstlichs und nutzlichs Kochbuch is a very interesting source and one of the earliest printed German cookbooks, predated only by the Kuchenmaistrey (1485) and a translation of Platina (1530). It was also first printed in Augsburg, though the author is identified as coming from Dillingen where he probably worked as a cook. I’m still in the process of trying to find out more.