France, 14th c.
Recipe by Daniel Myers
Mustard is actually very easy to make. While there were lots of different recipes in the middle ages, this one is typical, and the final product is perfect for serving with beef, venison, mutton, salted fish, and just about anything else. Surprisingly, it's also not very different from modern mustards.
4 Tbsp. whole mustard seed
6 Tbsp. white wine vinegar
1/2 tsp. sugar
1/2 tsp. powder douce
Put the mustard seed and 4 Tbsp. vinegar into a small bowl and allow to soak over night. The pictures below show the mustard before and after soaking. Note that the mustard in the "before" picture is actually another batch with slightly less mustard seed. It does expand when soaked, but not quite as much as pictured here.
The next step is to grind the soaked mustard seeds into a paste. As an experiment, I ground some of the seeds of my test batch with a mortar (which took about 20 minutes) and pestle, and the rest in a food processor (which took about 2 minutes). As probably cannot be seen in the picture below but was readily aparent to the naked eye, there was no difference at all in the end results. From now on I will save the time and effort and just use the food processor.
Finally, mix the mustard paste with the spices, sugar and 2 Tbsp. vinegar. It will taste very sharp initially, but will mellow out considerably if refrigerated for a couple of days.
Out of curiosity I did a side-by-side taste test, comparing this mustard with a well-known brand of store-bought Dijon mustard. The texture of the store-bought mustard was smoother, but that could be corrected with another minute or two with the food processor. The flavors were also different, but neither was notably better than the other - they both tasted like mustard.
MUSTARD. If you wish to provide for keeping mustard a long time do it at wine-harvest in sweet must. And some say that the must should be boiled.
Item, if you want to make mustard hastily in a village, grind some mustard-seed in a mortar and soak in vinegar, and strain; and if you want to make it ready the sooner, put it in a pot in front of the fire.
Item, and if you wish to make it properly and at leisure, put the mustard-seed to soak overnight in good vinegar, then have it ground fine in a mill, and then little by little moisten it with vinegar: and if you have some spices left over from making jelly, broth, hypocras or sauces, they may be ground up with it, and then leave it until it is ready.