There are two kinds of murrī, the more usual kind made using fermented barley, with a less common version made from fish (see garum). Almost every substantial dish in medieval Arab cuisine used murrī in small quantities. It could be used as a substitute for salt or sumac, and has been compared to soy sauce by Rudolf Grewe, Charles Perry, and others due to its high monosodium glutamate content and resultant umami flavor.
Originally a Byzantine condiment, murrī made its way into medieval Arab cookbooks, likely due to exposure to Byzantine culture during the empire's rule over much of what came to be the Arab world. Charles Perry, an expert in medieval Arab cuisine, suggests that murrī arose from garum, a fermented fish brine that was commonly used by the Greeks and Romans. As Arab lexicographers have noted that murrī is pronounced al-muri, with one "r", and suspect it is a word of non-Arab origin, Perry suggests that its etymology may be connected to the Greek halmuris, medieval Greek almuris, the source of the Latin salmuria, meaning "brine".
The recipe for murrī was mistranscribed with the fermenting stage omitted, in a 13th-century text Liber de Ferculis et Condimenti, where it was described as "salty water" elsewhere in the translation.
Traditionally, murrī production was undertaken annually in households at the end of March and continued over a period of 90 days. Barley-based murrī entails the wrapping of raw barley dough in fig leaves which are left to sit for 40 days. The dough is then ground and mixed with water, salt, and usually additional flour. It is then left to ferment for another 40 days in a warm place. The resulting dark mahoghany brown paste, mixed with water to form a liquid, is murrī.
A fast method for preparing murrī is to mix 2 parts barley flour to one part salt and make a loaf that is baked in the oven until hard and then pounded into crumbs to soak in water for a day and a night. This mixture, known as the first murri, is then strained and set aside. Then, raisins, carob, dill, fennel, nigella, sesame, anis, mace, citron leaf, and pine seed milk are boiled with water and strained. The second murri is then added to the first, and boiled until thickened.
Murrī mixed with milk was known as kamakh.