Please incorporate any stories if any to showcase the tradition
I cannot say what a monk should do, so this answer is off-topic, and theoretical, for what it's worth.
I had e.g. here a very small amount of insight into conversation when there's a disjoint view of reality.
You might be worried that because the monk and the host have a different view/insight about the food, therefore it's not a topic/subject which they can share a conversation about.
I'd suggest that the 'monk' might try to react/respond to the person, not to the food. Perhaps something like, "It's kind of you to invite me" or "It's kind of you to care about my welfare" or just "It's good" ... and then try to reciprocate, perhaps inquire after the welfare of the person you're talking to.
Also my mum taught pre-schoolers. Part of her advice for controlling their behaviour was, instead of scolding them for bad behaviour, wait until they show some good behaviour and praise that. So you might not want to be scolding a layperson about impermanence. In fact the book described in this answer was written by a monk who deals with laypeople in Texas: and it claims, explicitly, that "impermanence" and "dukkha" and so on are concepts which were more intended for monks than for laypeople.
Please incorporate any stories if any to showcase the tradition
Here's one Zen story that could be relevant to what I was saying above:
No Loving-Kindness
"To think I fed that fellow for twenty years!" exclaimed the old woman in anger. "He showed no consideration for your needs, no disposition to explain your condition. He need not have responded to passion, but at least he should have evidenced some compassion."
I think a moral of that story is, 'Loving-kindness: don't leave home without it.'
An article like Detachment and Compassion might be apposite.
Here is another:
Brother Stream handed out clementines and we all learnt how to peel and eat the fruit slowly and mindfully, enjoying the bright orange colour, the citrus fragrance and the crisp sound as we each held a Clementine up to our ear and gently removed the peel in one long piece, before holding a segment in our mouths and enjoying the taste.
This one is a bit different:
- It's with school-children
- Eating is just one activity (read the article for the 'bell' before eating and the 'singing' afterwards)