The stew I've been planning as inspired by Eulalia's recipe is presently simmering, so now is a good time to blog about what I've done. I've made substantial changes, as you will see.
1 1/2 pounds of beef stew meat, in chunks;
1 cup smoked bacon, in smallish chunks;
1 medium-sized apple (I ended up with a Braeburn apple from the supermarket), cored and chopped;
1/3 cup pearled barley;
1 cup apple cider (i.e., cloudy apple juice);
4 leek stalks (white and light green parts), chopped moderately fine;
2-3 teaspoons of dill-spiked sea salt (the blend was specially-made by a vendor I know).
In a separate pot, bring the barley to a boil, then let it simmer in about 3 cups of water until it has at least doubled in size (about 1 hour to 1 1/2 hours). Then place all ingredients into a crock pot and cook on high heat for about an hour, then turn to low heat for another 9-11 hours until the meat is thoroughly cooked.
Eulalia's idea to cook the barley with the rest of the stew is probably a more period approach than mine. However, as her recipe suggests, it carries a greater risk of burning the stew. With my method the stew can be left for long periods untended. I resisted the temptation to add black pepper (which would not have been period) but dill is, at least for England, and so far as I know leeks are. I could have added mustard powder, but decided that would clash with the apple and apple juice.
Meanwhile, I have tracked down the ingredients for making the Hurtswic "Viking" flatbread! Since the dough can be refrigerated, I figure I'll mix the dough and try cooking some to go with this stew. The Hurstwic recipe does not specify which proportions to add of the oat, barley, wheat and rye flours; I figure I'll try equal proportions for the first batch. I'm also adding walnuts. My husband agitated for the addition of cranberries (he loves cranberries with walnuts in anything) so I'm making half the batch with cranberries even though this is pretty much non-period (I could use cherries, which are arguably period for Ireland, at least, but my husband likes cranberries more, and this isn't really meant to be a rigorous experiment).