I did not succeed in gently heating them in the water for hours, as Bach suggested in "Carolingian Foodways", but I turned them down to a simmer and simmered them for about 10 minutes. Then I stirred in some English mustard and some salt, and heated them in a bit more water before draining and serving them.
Fresh out of the pot, they were pretty bland, but my husband and I made some post-cooking additions that made them quite tasty, namely:
- More salt.
- Butter (Bach expressly suggests doing this, if the bacon used is not very fatty).
- A little garlic powder.
My husband suggested that the next batch should be simmered longer (true enough, but it was getting late for lunch, and we were both hungry) and that a lot more onions should be added. He also suggested adding dill, which I have mixed feelings about. (Dill is certainly a period addition, but I don't like the flavor of it very much.) I also think adding fresh garlic would be useful, and will do so next time. Perhaps that's getting a bit fancy for what was very basic food in period, but onions and garlic were certainly available, and people do tend to use what resources they have to improve their food.