Books with food instructions were produced for and by professional cooks who used ingredients that peasants and townsfolk had never seen.
Training and skill were assumed, just as the old Betty Crocker books assumed you knew how to separate an egg or melt chocolate. In fact, most of the information was “assumed.” Early cookbooks were just notes made by one professional for another. Everyone knew how to make a meat pie or soup; the book’s instructions just suggested a few spices or ingredients that the cook might not have thought about.
Standard weights and measures were extremely important in the marketplace, but they had not been developed for the kitchen. Most spoons were a certain size, but the “teaspoon” and “tablespoon” distinction was not formal. Many recipes just didn’t indicate amounts, on the assumption that a trained cook understood how much ginger was needed. I’m put in mind of a long-ago anecdote about a teenage girl trying to make a pie, and misreading the recipe such that she put in one cup of nutmeg, not one teaspoon. No medieval cook could make this error!
Although measurements were not always provided, some early cookbooks tried to suggest measurements of time. We sometimes teach young children to estimate seconds by the amount of time it takes to say “Mississippi.” Medieval cooks used similar tactics based on common prayers; time could be suggested in units of “Pater Nosters.” Longer amounts of time, beyond ten or twenty Pater Nosters, might be suggested as “the time it takes to walk a mile,” as modern city-dwellers might say “I won’t be long, go once around the block and I’ll be done.”
Medieval cookbooks had many references to spices, but very few to vegetables. This might be because professional cooks considered vegetables too easy, like giving directions around town by commenting “first, read the stop sign.” It might be that vegetables varied by season, and cooks used their own judgment and supplies to throw in parsnips or cabbage if they had it on hand. It might also be that professional cooks didn’t serve very many vegetables. Most recipes are about ways to cook and serve meat, the food of the upper class. Medieval kitchens prided themselves on having a large carbon footprint, as we’d call it. Consuming meat puts the diner at the top of a food chain, and consuming a lot of exotic, hard to raise/hunt meat puts the eater at the very top. That’s where professional cooks and their notebooks operated.
After 1150, book production increased. It was driven by the growth of universities at first, which meant no cookbooks. In the next two centuries, paper began to displace parchment. There were more and more books, and by the 14th century, scribes were copying out practical topics, not just academic ones. By 1400, you could buy a book on farm management, advice for women, veterinary diseases, chess, hunting, or one of the new scientific inventions like the astrolabe and place-value number systems. There were more cook books, too. Eventually, these included books aimed at the middle class.
Le Menagier de Paris, as we know it now, was written by an elderly husband for his teenage wife (perhaps on the assumption that she would well outlive him). The book is highly instructional and detailed, leaving little to the imagination. We can see, then, that this much instruction about cooking was considered generous:
“GRAMOUSSE is made from the cold meat of the hare left over from dinner and the stock of this meat also left over, in the following manner: first, beat four or six eggs, that is both white and yolk, and beat and beat until they flow like water, for otherwise they will curdle; and add as much verjuice as the eggs, and boil with the stock; and elsewhere cut the meat into strips, and put two pieces per bowl, and the broth over them.”