It's always worth watching Max (Miller of Tasting History)'s work (link to YouTube video on Kishkiyya from Baghdad). And we can always add more!
A little investigation on the antiquity of Kishk (كشك), a popular processed dairy food also applied to various grain products. Could it be the Sumerian ingredient kisimmu?
Kishk (كشك) relates to barley flour and bread, as well as a dried yogurt product. It also developed into a porridge-like dish made from barley and yogurt, what Max makes in this video, keškiya or Kešk bābeli.
It’s possible that a version of this dish is attested in the 1st millennium BCE, as referenced in tablet 2 Rawlinson plate 60, no. 1 (P395487). Published in 1866, it took over six decades for scholars to make any sense of this text. Text artifact is here.
Erich Ebeling’s “Tod und leben nach den vorstellungen der Babylonier” (1931) suggested that the text “describes the fate of people after death before the underworld court.” We better understand the text now as a parody, most recently discussed by Enrique Jimenéz (2017).
The parody was called bulṭī lū balṭāti (“live, yes live!”). It has purposely erroneous information about deities, a self-praising hymn by the goddess Ishtar, several absurd omens, and a famous section about a jester who reportedly could do anything, albeit terribly.
The part that we care about is the end, where “dietary prescriptions typical of hemerologies are ridiculed with coarse humor.” In the month of Kislimu (Nov/Dec), the texts suggests “you eat donkey dung on bitter garlic and chaff in sour dairy (kisimmu).”
Super gross – yet, we get to see some essential ingredients to what would be keškiya, which is grain and kisimmu, usually translated as “spoiled milk”. But that's actually the edible part of this recipe; it’s the grain chaff that is inedible. We're obviously ignoring the literal shit from an ass.
It’s thought that this word is a Sumerian loanword, usually written GA.HAB, meaning smelly [HAB] milk [GA]. It’s used in some legitimate Old Babylonian recipes, such as YOS 11, 25 (P291955) and 26 (P309744). In those texts, we'll see that it cannot be milk. I think it might be Kishk.
It’s described as being able to be mashed (ṭerû). It is also an ingredient for an Elamite broth called Zukanda; Elam existed in what is now Iran, exactly where the word Kishk originates. For the record, we do not really know what kisimmu means, only that it is a dairy product.
I don't have a smoking gun to make this an open and shut case, but I think there are enough similarities here to try. Thanks to @tastinghistory.bsky.social for giving me an article idea!