The first precept of Buddhism is ahimsā, non-violence towards living things. So, a vegetarian might assume that Thai food will be largely vegetarian. However, Thailand has a lively, complex culture, of which Buddhism is merely one part, and in reality, it can be surprisingly hard to find vegetarian food.
The cheapest food vendors, the street sellers, tend to stick to a few meaty staples: noodles with meat, rice with meat, and meat-on-a-stick (and its variants, sausage on a stick, fish on a stick, squid on a stick, frog on a stick, unidentifiable chunks on a stick). Finding a street vendor selling vegetarian food is a novelty, and as they often don’t speak much (if any) English, you might struggle to get across that you don’t want any sort of flesh. Even a dish of omelette-and-rice is questionable, as delicious Thai omelettes are often flavoured with stock, which may or may not be vegetarian in origin.
One step up in price, and flexible vegetarianism is easy in Thailand – as long as you don’t dig too deeply. Many an inexpensive restaurant will offer a meat-free version of Phad Thai (fried noodle, generally lightly-spiced and incredibly delicious), but Phad Thai is generally made with fish sauce (nam pla), and you might decide you’d rather not know about the stock in the omelettes!
Of course, if you are ‘nearly vegetarian’, in the sense that you eat fish (technically this makes you a pescatarian!), then Thailand should delight your taste buds. Its long coastline and bountiful rivers have ensured that seafood and fish are a major part of its vibrant culinary tradition. A prawn (shrimp) option of a normally meaty dish (such as a Phad Thai Kung – fried noodles with prawn) is usually easy to find, and local fish dishes can be terrific.
For the strict vegetarian, however, your best bet is to find self-consciously vegetarian eateries: at last count there were 27 in Bangkok, 20 in Chiang Mai, 5 in Phuket, and 2 in Chiang Rai. Or seek out organic and health-focused restaurants, or a tourist-oriented venue which has worked out that it needs veggie options for Westerners.
At the very worst, if you’re in a tourist town like Phuket or Chiang Mai, you’ll be able to find plenty of pizza places. But with a little persistence you can find plenty of vegetarian Thai and fusion food – it just might not be as easy as finding more meaty options.
Another option is to get to know your local street vendors and restaurateurs/café owners – very often if you give them enough notice, they will cook something up just for you!