What does a vegetarian do when invited by a smiling, rough-and-ready truck-driver in Eastern Turkey to join his family for dinner in a small village at the end of a long, dusty track? In many ways, limitations on what you eat, what you do and where you will go are anathema to the traveller. An open mind and a willingness to adapt make a much better approach. However, we all carry a few ethical ideas in our mental rucksack, and some of these principles are worth keeping. After all, we preserve our own moral standards when at home - even if the 'locals' don't agree with us - so it's reasonable to do the same when abroad.

For vegetarians, this isn't easy. It's not just the food, but attitudes. In most parts of the world, vegetarians are regarded as mere harmless foreign lunatics. Certain countries do have vegetarians of their own: they generally have either opted to give up meat for health reasons, or they are enjoined to do so on religious grounds. Some in Europe (mainly Holland and Germany) have a political commitment to avoiding meat because of the waste of resources that it entails. Few outside the Anglo-Saxon world have any sympathy with the notion (or have even come across it) that wantonly killing animals is actually wrong. Indeed, if they were to hear it, most would fiercely oppose the idea.

A problem arises when your morality is totally at odds with that of the people around you - especially when your views are seen as a Western luxury or as an absurd ethnocentricity.

Culture and circumstances impose a diet that is right for a given people. So it can sometimes be wise (if all you want is food and no arguments) to offer the most acceptable explanation for your own vegetarianism. Among friends this may not be necessary. In everyday encounters, however, you'll get the best out of people if you can either claim to be "on a diet", possibly under medical supervision, or dress up personal ethics as part of some religious persuasion. Above all, don't try to persuade people that they, too, should give up meat.

On the road it's essential to be flexible. Even meat-eating travellers may be faced with food (sheep's eyes, for example) that they find hard to swallow. My approach is simply to avoid meat and fish as much as possible. Usually it is possible, and with no greater hardship than a rather monotonous diet at times.

In Greece, for example, a vegetarian must be happy with lots of delicious horiatiki salad, fresh bread and oily vegetables; or, in France, some marvellous four-course meals in which the main dish is always omelette; or, in a dozen other countries, meals consisting entirely of snacks or a succession of starters. Some countries are easier than others. In Italy, where pasta usually comes before the main course, it usually is the main course for vegetarians. Mercifully, Italy is one of those places where nobody bats an eyelid at such eccentricities, and pasta comes in a score of different forms with a dozen different meatless sauces. Meatless pizzas are everywhere, and many Italian cheeses, such as gorgonzola, are made commercially without animal rennet.

In north-west Europe, eating habits are decidedly meaty, or fishy (especially in Scandinavia). But there are so many vegetarians that almost all cities and a good number of provincial towns have eating places that cater to meat-free consumers. Holland and Germany, like Britain, have thousands of such establishments. You can hit cultural differences with your fellow vegetarians, though. For example, to a typical Anglo-Saxon lacto-vegetarian (i.e. milk products allowed) there can seem a streak of masochism in the monastic simplicity - the alcohol-free, raw food veganism - espoused by so many Scandinavian vegetarians.

Further east in Europe, there's a hefty meat culture - often just artless slabs accompanied by potatoes and cabbages, and followed by lard-rich sticky cakes. This is not invariably the case. The Czech Republic, or at least Prague, seems now to enjoy an abundance of cuisine of all kinds.

One of the best parts of the world for vegetarian travellers is the Middle East. Israel, above all, is a land of meat-free snacks and meals. All sorts of cultural reasons account for this. Many Jews are vegetarian, but in any case Jewish dietary laws prohibit the mixing of meat and milk within several hours of each other. This has led to a proliferation of 'dairy' restaurants in which nothing on the menu (not even the cheese) contains any meat products. Note, though, that dairy restaurants do serve fish.

Israelis particularly like salads, even for breakfast, eaten with yoghurt-like milk products. More salad at lunch time or in the evening is accompanied by fried, meat-free items such as falafel (like meatballs, but made of chickpeas), blintzes (filled, rolled pancakes), latkes (fried grated potato) and borekas (little savoury pastries with fillings). Some of these have been brought to the country from Eastern Europe, others are native Middle Eastern dishes, reflecting the differing origins of the refugees who make up Israel's population.

In neighbouring Arab countries (not the Maghreb, though), and in Turkey, several of the same delicious snacky dishes can be found. A traditional Arab mezze (a meal consisting of many small items served all at once) can be made of such dishes, although in the Islamic world it is hard indeed to get anyone to accept that you truly don't want any meat.

That's not particular to Islam. In much of fervently Christian South America, meat is the be-all and end-all of cookery. While I was in Brazil, a crisis involving farmers led to meat shortages that actually sparked off riots - even though nothing else was in short supply. There I managed happily, mainly on salads, fruit and bread. North America has followed a similar path, despite closer historic links with north-western Europe. True, there's a good magazine called Vegetarian Times (website www.vegetariantimes.com), and hundreds of 'veggie' eateries scattered about - in the big cities or around university campuses - but on the whole North America is still hooked on meat. Often the only alternative seems to be a cheese sandwich (with dubious American 'cheese'). One consolation: American vegetarians are not usually into austerity and self-denial.

It's perhaps too reminiscent of holiday-makers who go abroad loaded with the familiar foods of home, but don't be unwilling to put some emergency rations in your luggage. I have staved off hunger on countless occasions - and in every continent - with a small bag of muesli mixed with milk powder. It can be turned into a nourishing, tasty and filling snack just by adding water. If there's milk, yoghurt or fruit juice on hand, so much the better.

The one country where vegetarianism is really normal and meat-eaters in the minority is India. Hindus are supposed to steer clear of all meat (including eggs), but yoghurt is eaten in abundance. Most Hindu eating places at the poorer end of the scale are completely vegetarian, as are the smarter (but entirely un-Western) Brahmin restaurants. Travellers tend to find themselves in a different class of establishment, quasi-European in a dignified, old-fashioned way, as if the days of Raj were not quite forgotten. Railway stations, for example, usually have a good dining room divided into meat and vegetarian sections. Many hotels do likewise. Muslim or Christian regions, say Kashmir or Goa, are less reliable. But similarly, beyond India, pockets of Hinduism provide resources throughout South-East Asia.

The places where vegetarianism is best known, and often quite well catered for, tend to be those countries formerly under British influence. Australia - which also benefits from Middle Eastern and Indian immigration - is an obvious example. And, though most major scheduled airlines have now come to grips with providing meatless tray meals, it's not for patriotic reasons that I often commend British Airways to vegetarian travellers. They are more aware of what vegetarians want and more serious about providing it than most of their competitors. When booking, you can opt for lacto-vegetarian, vegan or Oriental vegetarian in-flight meals. Other airlines capable of providing (rather than just promising to provide) a decent meatless meal include Air India, El Al and Swissair.

But to return to earth. I did accept the Turkish truck-driver's invitation. A goat was slaughtered and served, with no accompaniment but bread. I picked reluctantly at the meat, hoping no one would notice. While we men ate and the women peeked from the kitchen door, the severed head of the animal gazed at us horribly from the end of the table. Rough drinks were poured and we toasted mutual understanding.