Last year, my company trip was at Bangkok. It was more of a shopping trip so everyone stayed in shopping malls and day and night markets. I do prefer very much to do sightseeing instead. Anyway, I ate food from vegetarian places whenever I had the chance not to dine with everyone else :) Managed to get some pictures of the food.
The 1st night, my company decided to have a late dinner at MBK basement. I was thinking I would have to ask the restaurant to dish up something vegetarian, but luckily Nova kitchen was just a few steps away. So I went there and packed their khao pad thai back to the non-veg place my company was eating at.
Nova kitchen serves vegetarian food and non-vegetarian food. This Khao pad thai was actually not from the vegetarian menu. But I was looking for something distinctively thai and not some "chinese with a twist of thai" food, so the waitress suggested this dish from the non-veg menu and say they could substitute the meat with mock meat to make it vegetarian. Costs 80 baht.
The next day it was shopping at Platinum plaza. Platinum plaza is mainly clothes, shoes, bags etc., but on the top floors you will find a few stalls selling some gifts and crafts - not the cheapeast place to buy your gifts and crafts though...The top floor also has a food court with a vegetarian stall, and I ordered the soup noodles.
The noodles is actually a kind of thai vermicelli, hidden underneath the veggies and stuff. Their soup noodles is what I classify as "chinese with a twist of thai" - having more fried bits in it. The soup was pretty much usual with the light pepper taste, but good if you are looking for something lighter after all those spicy and deep fried stuff.
Finally my lunch at MBK food court - beancurd rice... which ended up being mock meat rice. With pickled ginger (pink) and some tomatoes which tasted not really like tomatoes. The chilli you see in the picture is really really hot. Pretty much Singapore-styled otherwise.
For cheaper deals on your goods, try the chatuchak weekend market or suan lum night bazaar instead of shopping centres. I didn't come across any vegetarian food eateries in these two places though.