Again, from the Innsbruck MS:
75 If you would make a jelly (sultz) of four colours, take calves’ feet or sheep’s feet and boil them until the bones fall out, and then make the sultz with that. The green colour is made with parsley juice, add the feet to that and let them boil together and pass them through. The black colour is made with tart cherries (weichsel) or with dark toasted (prenten) bread, also add the feet to that. The yellow is made with saffron. Season all four colours. The white is made of almonds or nuts. Pass them through, and boil each colour separately and add a little wine, but not to the white. When they gel (gerün) and you wish to serve them, rub a serving bowl with honey, and let the jelly (sultz) harden (uberslahen) so it does not run together.
This is a lovely example for how medieval cooks played with colour. In this case, it is apoplied to jelly, a fashionable food that may have been quite a novelty still at the time. The process of extracting gelatin from bones and connective tissues is described here, which clarifies the meaning of sultz in this case. That word, a cognate of Sülze and related to Salz and Latin salsa, could still refer to either a bread-thickened, spicy sauce or to a gelatin and sometimes to a cross between the two, which may be the origin of the jelly.
The colouring agents are not surprising: Green is produced with parsley juice, black with dark toasted bread or tart cherries, presumably their juice or a preserve, yellow with saffron, and white with almond milk. These are common colourants at the time and recur in other recipes.
We are not told how to serve the jelly, but the instructions to spread honey on the serving bowl and the reference to jelly running together (always a risk with imperfect quality control and no artificial refrigeration) suggest that it was cut into shapes and arranged on the bowl, possibly in a pleasing pattern. A similar recipe from the Königsberg MS imitates a chessboard.
This is still a long way from the jellies of the Renaissance both in terms of flavour – it cannot have been terribly attractive compared to the sweetened wine concoctions of de Rontzier – and its architectural ambition. But it represents the beginning of a grand tradition and an established medieval habit of conspicuous display: If you could not make your food interesting in terms of taste, you could still make it colourful.
The Innsbrucker Rezeptbuch is a manuscript recipe collection from a South German/Austrian context. It dates to the mid-fifteenth century and survives as part of a set of medical and culinary texts bound together. The editor Doris Aichholzer published it together with two related manuscripts and drew attention to the less elaborate, more practical recipes. The manuscript is of unknown provenance, but has been owned by the Habsburg emperors since at least the early sixteenth century. It is now held at the Nationalbibliothek in Vienna. An edition, German translation and commentary can be found in Doris Aichholzer: Wildu machen ayn guet essen… Drei mittelhochdeutsche Kochbücher, Peter Lang Verlag Berne et al. 1999