I apologise in advance for typos here - I’m currently typing on my phone in Dublin airport, on my way to an SCA event in Wales, where I’ll be eating and helping to cook medieval-style food for a week while camping at a castle. So the question feels timely.

1. Your hypothetical monk would notice the differences if he was coming from pre-Norman Ireland. The Vikings don’t seem to have had much impact; they largely ate what was there rather than introducing anything extra, although the amount of rye grown when they were around may have been a bit higher. The monk would have been used to porridges, oat bread, barley beer, dairy products in large amounts, a good bit of fish, small amounts of meat, and a lot of onions and garlic, among other vegetables. In England, he’d have encountered wheat and barley bread (though likely not of a high grade), much less dairy, probably less fish, somewhat more meat (maybe), a different selection of vegetables with less in the way of alliums, and while the barley beer would still have been there, he might also get wine. Wine wasn’t unknown in Ireland, but was expensive. I believe England would also have had more pottage (stews and soups, roughly) and less porridge. After the arrival of the Normans, that difference was gradually lost, except in the far west. By 1650, particularly in the Pale, you’d have had a tough time knowing which island you were on from the food.

2. It’s pretty fair to say that all of traditional Irish cookery was lost. We have no written sources dealing directly with cookery, so we’re operating on deduction and archaeological evidence for cooking techniques, with recipes being pretty pure guesswork. However, this didn’t really happen until the 17th century and the arrival of the potato, which wiped everything else off the menu pretty quickly. Before that, there may have been a few surviving techniques or handed-down recipes (particularly for cheeses and beer, which need a degree of precision in making). The degree to which other foods disappeared is best illustrated by letters written in the early 20th century by a Gaelic League member staying in the Aran Islands, asking his brother to send him some peas, as the islanders had never seen any.

3. Consequently, almost all of modern Irish cuisine - such as it is - is the result of colonial occupation. Bacon and black pudding may be holdovers, as they were practical throughout. Oat bread is probably much the same, although most Irish people are unfamiliar with it. We still eat more dairy than in England, but that’s a modern re-development, not something that survived. Cabbage isn’t much eaten anymore, but would have been a survivor from late medieval diets until the mid-20th century. And that’s about it. Because of the association with poverty on the one hand and fast days on the other, foraged foods and fish are still largely off the Irish menu, but I honestly think that’s on us, not the British.

4. British views on Irish anything were as inaccurate through history as they are now, being blunt about it. However, the conviction in the 1800s that we lived on potatoes with the skins on, milk and fish was pretty correct - and because that’s a pretty complete nutritional profile, we did good on that diet. Irish labourers were valued for their strength and health, having been raised on that. What the other beliefs about Irish food actually were, though, is outside the scope of the research I’ve done to date.

Right, boarding. Followups will be slow, for which my medieval-ish apologies!