Composts (gumpost), from the Latin compositum meaning combined or mixed, were a kind of mixed vegetable pickles many recipes for which survive. The texts usually describe complex mixtures including expensive spices and dried fruit, but it is likely much simpler ones existed. By the fifteenth century, compost also describes what is clearly sauerkraut.
If you would have sour compost, pour on vinegar with sour yeast and ground mustard. Or boil wine or water with cream of tartar (win stein) and let that become clear, and pour it in (to the compost) with chopped raw onions.
8 Sweet Compost
Sweet compost: wash young chard and scrape the roots, and boil it in salted water. Then place it on a board until it is drained. Take honey and wine in equal amounts and boil it in that, and (add) figs and both types or kinds (baidertail oder lay) raisins. Colour it and pour it on the chard, and strew anise and almonds on it. You may also add medlars and pears if you like.
9 Sloe Compost
Sloe compost: take wine and honey in equal amounts and boil it. Then take sloes, well-prepared, and lay them into this (when it is) cold. You may also stick pears and medlars with spices. Take as much as you wish to serve each time, that way the spices retain their power and goodness.
As far as I can see, only #8 is a more or less complete recipe. #7 describes how to give a compost a tart flavour. This could be used with any mixture of vegetables. I am less certain about #9 which may desribe a technique for preserving sloes. There are parallel recipes describing other fruit in honey wine. I rather suspect, though, that this is a more general instruction either for preserving fruit or for sweet composts with sloes or pears and medlars, the latter two stuck with spices, added to the mix. The description of pears and medlars stuck with spices is reminiscent if recipe #17 in the Mittelniederdeutsches Kochbuch:
17. If you would make pickled quinces, boil them well in good, old beer to their measure. Then cut them in quarters and cut out the core (kernehus, lit. house of the seeds) or that which attaches to it (?). Stick them all about with ginger and cloves as many, as you would have in there. Lay them in a good, clean cask. Pour good, pure honey over them. That way they are pickled quinces (sultqueden).
Bound together with medicinal, veterinary, and magical texts, the culinary recipes of Munich Cgm 384 were partly published in 1865 as “Ein alemannisches Büchlein von guter Speise“. The manuscript dates to the second half of the fifteenth century. My translation follows the edition by Trude Ehlert in Münchner Kochbuchhandschriften aus dem 15. Jahrhundert, Tupperware Deutschland, Frankfurt 1999, which includes the first section of recipes not published earlier.