DP, who eats almost everything (except for oily fish, salmon and big pieces of mushroom), told me years ago that the family had gone and stayed with an American friend & family when he was a teenager and he didn't like the food at all; he said it 'tasted weird'. He was working over there last year and, despite having access to free food all the time, lost the best part of a stone because, despite trying, apparently the 'weird' tastes were still present in everything. He spent the entire time living on fresh fruit.
I wonder if it's something to do with how farm animals are reared, together with the processing, high fructose corn syrup and all the other ingredients that are not present in UK/EU products? I know that UK Heinz Ketchup is seen almost as a health food alternative because of the lack of HFCS and flavourings, for example.
I've cooked Quorn mince for a veggie friend - it takes a lot of work to make it taste and have the texture of something other than cotton wool, polystyrene and sadness, so I spent roughly double the usual time in the kitchen, carefully adding ingredients, spices, cooking it down, adding some oats for texture, etc, to create something that was pleasurable for all of us to eat. I think it would have been easier to just use lentils - or, do my usual thing where I know there's a chance there might be some dietary requirements to allow for - a couple of vegan vegetable/potato/pulse curries with the option of yoghurt of some type for those that wanted it, plus flat breads.
I'd need to know in advance if somebody had allergies, though (and whether they're one of those people who detest coriander) - and I'd ask if anybody had them so I could not only make sure whatever they were allergic to wasn't in the food, I'd want to make sure it wasn't in the house and everything was washed/cleaned again immediately prior to cooking for them.
Having endured some awful meals as a teenager where I've had to be polite to somebody's Mum, I don't ever want somebody to come away from our house thinking the food was shit or I tried to get one over on them. I just want them to enjoy themselves.
Pity the OP's friend was apparently looking for a 'conversion meal', rather than that.