German cuisine loves to serve cowberry or redcurrant sauces with roast meat, especially venison. I did not know how far back this tradition goes: Here is a late sixteenth century description with interesting pointers to the distinction between medicinal and culinary preparations, and the proportion of sugar to juice.
How to preserve them
(marginalia: currants, how you should preserve them)
Pick them after St John’s Day (Johannis i.e. 24 June) when they are quite ripe and press them through a sieve, cloth, or colander (Sieb, Tuch oder Durchschlag). Then put the same juice into a glazed pot and boil it until it turns thick, and add plenty of sugar that must also be boiled and clarified (gereiniget), and use it as a dipping sauce (Einstippe oder Eintuncke) when you eat roast. You may also stir in ground cinnamon if you wish, and nutmeg or mace, you are free to add those, they do not spoil it. This juice cools nicely in summer.
Many make it thus: The berries are picked and skilfully crushed in a mortar so that the seeds stay whole, and then pressed out through a coarse cloth. Apothecaries use a press for this in which it is pressed out skilfully so that no seeds are pressed out with it. Take half a pound of this juice and two pounds of Canary sugar. Boil up the Canary sugar just one (nur einen frischen Soth), add the juice and let it boil up once again. Take off the pulpam (pulp) and the spumam (froth) with a spoon, thus you have the proper succum Ribium that strengthens the heart and is a proper, strengthening succour to the sick when they suffer great heat, strengthens the lungs, the stomach, and the liver, and remains good and potent up to ten years.
Make Ros Ribium thus: Take currants, press them out as described above about the juice. Take one pound of the juice, let it boil up once, take off the spumam (froth) at the top, and let it boil. Try it out once or three times on a table or plate so that it does not become too firm. Thus you have the proper Ros Ribium, nicely pure and clear, serve it as a dipping sauce for a lordly table (Herrentafel).
The ready use of Latin suggests these recipes belong at least in part to the realm of the apothecary. Assuming that the 4:1 proportion of sugar to juice in the medicinal preparation represents the absolute maximum, there is still considerable scope for sweetness in the other preparations. They are also boiled longer, much as traditional jams and jellies are to reduce water content. The test for consistency described in the final part is still familiar to anyone cooking jam as Gelierprobe. Plus ca change…
Johann Coler’s Oeconomia ruralis et domestica was a popular book on the topic of managing a wealthy household. It is based largely on previous writings by Coler and first appeared between 1596 and 1601. Repeatedly reprinted for decades, it became one of the most influential early works of Hausväterliteratur. I am working from a 1645 edition.