Neil's Guide to being a Vegetarian in Thailand . . .
The Thais are a tolerant people who have seen off many would be invaders in their time. From the Colonial French and the British Empire to more local and recent would be usurpers like the Burmese and through it all they've held on to their individuality with a smile. The Thais love to help and you'll find that whether or not you succeed in your endeavors, whatever they may be, you'll find you appreciate the constant aid you'll receive from them. Trying to hold to a vegetarian diet here is one such endeavor you'll need all your wits to survive. As I mentioned earlier the Thais are very accepting and whether or not they understand your desire to eat only vegetables they will do their utmost to help you stick to it. However like many countries with a traditional bias in their culture the very idea of not eating meat will throw up some interesting dilemmas for them, so don't be surprised if after you explain you don't eat meat you are presented with a plate of noodles and a smile only to discover after tucking in with vigor that the stringy bits aren't tofu. This last time we faced this scenario our ever helpful waitress informed us, "it's ok it's only chicken." After a few minutes of pleading she finally removed the plate only to return a few minutes later with the same dish, after they'd sieved the meat out first of course. Beware also of Tuna, which the Thais seem to regard as the great vegetable of the sea and of course remember that some vegetarian dishes have vegetables in them amongst the meat.
It's not all bad news of course and there are plenty of vegetarian restaurants and dishes available at bigger restaurants. The Thais are anything but stupid and as they realize the custom that escapes them by simply not having a few options on their usually vast menus the practice will change.
Remember also that Thailand is very close to India and as such there are many Indian restaurants, which serve excellent veggie fare. You'll find these mainly in highly populated and tourist areas.
To order vegetarian food the simplest way is in Thai. The Thai language is tonal so don't worry about tenses and just go straight to the point. To say 'I want vegetarian food,' you have to say 'Ow (like being hurt) aahaan (this has a rising tone like a question) Jay (just like the letter). Or you could ask 'have you got vegetarian food?' Just say this 'Mii (me) Aahaan (again the rising tone) Jay (as before) Mai (my). So to recap on that...
'I want vegetarian food,'...'Ow aahaan Jay'
'Have you got vegetarian food,' ... 'Mii aahaan jay mai.'
One thing to be cautious of, for the serious vegetarians amongst you, is that the produce here has the list of ingredience written firstly in Thai, and rightly so, and then sometimes in English and sometimes in a blend of English and Martian but sometimes only in Thai.
This means that it is almost impossible to work out whether a product contains an animal by product such as gelatin or calf rennet or the like. Also beware that, unlike the west, products like noodles and potato chips have a tendency to contain traces of meat.
When traveling as a vegetarian to Thailand it may be wise to obtain vitamin supplements in advance just in case you're traveling off the beaten track. Having said that if you are prepared to stick to noodles and rice in the less traveled regions and feast whenever the opportunity arises then Thailand could be heaven for all of us veggies as there are so many fresh fruit and vegetables produced here.
Vegans and Fruitarians by contrast will thrive in Thailand as dairy produce here is produced mainly for the tourists. With the locals preferring soya milk and having little love of cheese (which doesn't seem to last long in the heat.) With a little knowledge being either a vegan of fruitarian would be a breeze, the latter will be stunned at the range of fruit and nuts and seeds on offer here in Thailand.
In summary just remember that although most Thais are Buddhists and Buddhists do not sanction the killing of animals for food. Most Thais however work on the principle that the animal was dead before I bought it.