By Richard Black
BBC News, Shimonoseki, Japan
It was a situation which no amount of training in etiquette could equip you to deal with - not that I have had any such training anyway, as anyone who knows me would affirm.
Whale meat is openly advertised for sale in Japan
I was in a waterfront cafe in Shimonoseki, a long-time whaling port.
In front of me was whale meat, from an animal which it is simply unthinkable to eat in Britain - so unthinkable that I had to promise my daughters I would not touch a morsel of it during my time in Japan.
Yet once in Japan, nothing seemed more normal.
Whale meat was not everywhere, as tuna or tofu are, but in every city I visited I came across at least one restaurant which served it in some form.
So what should I do?
I had come to Japan for the BBC's One Planet programme, to look at where whaling sits in the history and culture of a country which gets a huge proportion of its food from the sea.
In most parts of Europe and North America whales have become iconic, sacrosanct, no more to be killed or hurt than your close relative.
But in the Japanese view, they are a wild natural resource to be used, just like fish or lobsters or rabbits or boar.
And the more I have thought about it, the more complicated the arguments have grown.
Firstly there is conservation. There is a popular view that all whales are endangered - and many species are, but by no means all. And it certainly was not Japan that drove some species towards extinction.
The Americans, Brits and Norwegians did that, with a bit of help from the rest of Europe and its former colonies. Has it become convenient to blame Japan?
Harpoons are another issue.
On board a retired whaling ship I met Akira Okiyoshi, a harpooner who spent 30 seasons hunting in Antarctic waters.
With fire returning to his 80-year old eyes, Mr Okiyoshi showed me how he used to aim as the deck jolted up and down in the Antarctic swell. He unscrewed the tip of the harpoon, where an explosive charge was placed, a charge which would detonate inside the whale.
I could not help but picture the splash of flesh as the cold metal struck home.
Akira Okiyoshi relives the past on the Toshi Maru
Then Mr Okiyoshi explained that usually the first harpoon did not kill the animal - that would need a second firing, perhaps a third. A cruel way to die?
Then I thought of the battery farm I had visited as a child in England - the hens cramped together five to a tiny cage, trampling each other in order to win a few cubic centimetres of space.
I thought of abattoirs of fish impaled on steel hooks in the open ocean, of deer caught in snares waiting only for the relief of a huntsman's bullet, the peeled but still twitching frogs that I had seen in a Bangkok market years before.
Who decides, and how, which cruelties are acceptable, and which not?
At its 2006 meeting the International Whaling Commission saw a fascinating vignette played out.
Australia's environment minister was laying into the Japanese delegation in forthright style, casting them as ignorant slaughterers of cute and special creatures. The Japanese delegate replied by asking about Australia's annual "slaughter" of two million kangaroos.
Later I chatted with one of the Australian journalists who tend to write about whaling in pretty stark language, using phrases like "barbaric cruelty" whenever there is an opportunity.
Not only did this particular environment journalist see nothing wrong with the kangaroo slaughter, but they had actually been on the annual hunt, shot some "roos", and thoroughly enjoyed the experience.
Back in Tokyo, I sat one evening in a sushi restaurant dining with a young, modern urban Japanese lady who was tucking into some raw whale.
I asked whether she would ever eat dog. She looked shocked. No, no, she told me, it would be unthinkable - but her whale was delicious.
Why is it OK to eat horses in France and Italy but not in Britain? Why do Finns proudly serve reindeer, and Icelanders puffin, while others recoil at the thought of eating them?
A few years before, in Vietnam, I had seen restaurants with cooked dogs hanging up outside, much as Chinese restaurants in Western cities display cooked ducks and slabs of roast pork.
So would Vietnamese people ever eat whale? Apparently not, I am told - it would be unthinkable.
So why the contradiction? Why is it OK to eat horses in France and Italy but not in Britain? Why do Finns proudly serve reindeer, and Icelanders puffin, while others recoil at the thought of eating them?
Does every society concoct its own list of what is acceptable and what is not?
Does every individual do the same? Is it just culture? And if it is, is there any hope of securing agreement between different camps on issues like whaling? Is it even right to try?
The most extreme example I have come across of what you might call "food anathema" involves frogs.
When I was a boy, a series of jokes went around my school involving some unpleasantness with frogs in liquidisers.
Blended frogs are sold as a health drink in parts of Peru
Well, a couple of years ago a South American researcher showed me that it actually happens.
In a market in Peru he had come across a stall selling Extracto de Rana - frog extract.
Live frogs would be liquidised with honey, malt and herbs to produce a supposedly healthy tonic drink.
That, I suspect, would be unthinkable - not to say undrinkable - in most cultures. If it were offered to me, I would turn it down... I think.
On the other hand, maybe if I spent long enough in the Peruvian highlands, Extracto de Rana might come to seem normal. But I was not in Peru, I was in Shimonoseki, with plates of whale pastrami and cutlet in front of me, being urged to eat.
Unthinkable at home, normal here. What was the right thing to do?
From Our Own Correspondent was broadcast on Saturday, 26 May, 2007 at 1130 GMT on BBC Radio 4. Please check the programme schedules for World Service transmission times.