Well, anything not in a sauce, really, most thai sauces will have sugar in them. Having said that, seriously, if you don't eat a TON of food, and you end up eating a little sugar, it's not like the world will explode. I went to my mother in law's 60th last night, and while I tried to be sensible, I didn't interrogate the waiter and I am sure I ate sugar. Today, I am off sugar again, and I am certain that so long as it's a once in a while thing, my body can handle it. I had to travel across the US for three weeks, and was surprised that I kept losing weight despite having dessert a few times here and there. I'm sure it would catch up with me if I ate that much sugar regularly, but, it's my experience that if you're stuck, there's no need to be a pariah, just do the best you can and get serious again the next day.
The caveat is, if you start to eat sugar every day or two using what I just said as an excuse, then you're going to end up paying the price. The downside for me was not so much weight gain, as being addicted again and having to battle through cravings to get completely sugar free again. I'm doing it (I was sugar free for a week before last night and am being EXTRA careful now there's no events on the horizon that might trip me up, I want to get in to the zone again ASAP ), but it would have been easier if I'd not had to travel, or if I'd been able to stay completely off sugar while I was away.