ACTUAL MEDIEVAL RECIPE:
Taken from ~Forme of Curye,~ ab. 1390 A.D. (Page 15r)
Take Funges & pare he clene & dyce he. take leke & shred hi smal & do hi to seeþ in gode broth. color yt wȝt safron and do þer inne pouder fort. and serve hit forth.
Take funguses and cut them clean and dice them. Take leek and shred them small and do them to seeth (boil) in good broth. Color it with saffron and do therein powder fort. And serve it forth.
NOTES of Interest
Notice there is no standard spelling, even within the same paragraph, nor capitalization at the beginning of a sentence.
Also, in addition to using a kind of shorthand for commonly used words (like "&" - not the same as ours, but there is a resemblance), medieval writers also had a few other letters we no longer use (my favorite being þ which is the voiced th sound in "this").
And, of course, there are no measurements. It was assumed if you could read, you knew enough about cooking to use as much as you needed. Medieval cookbooks weren't written for housewives! Some may have been written just for posterity's sake, but it is believed most were written for cooks of the nobility.
(Actually, it's possible many cooks couldn't read. They would likely have needed someone to read the recipe to them while they were cooking a dish the first time; hopefully they would remember it well enough to make it again later!)