Ramen soups are good and widely available, with or without noodles, I'm T1 so can just bolus for the noodles, have always found ramen stabilises me for ages, I've got this vague theory based on no scientific evidence at all that ginger and chillis seem to damp down spikes, although it's maybe just the fact that the dish is pretty much just water.
If you see anything involving Kampot pepper, try that: had a simple dish once in Phnom Penh, just some mashed potato and barbecued chicken, with an initially unpromising looking side dip sauce which turned out to be ground Kampot pepper marinated in lemon juice - as simple as you can get but the sauce wouldn't be out of place in a Michelin restaurant, real depth and complexity to it.
Dragonfruit are brilliant. Tesco did imported versions for a short while which were about the size of a tennis ball and cost 3 quid but over there, you can get rugby ball size ones for next to nothing, and the good news is they're 9gm carb per 100gm, which is on a par with most berries. They look like something from a strange planet in Star Trek. Nice melon style flesh with black seeds. In fact they're so weird, am gonna have to post a photo:
The Foreign Correspondents Club in Phnom Penh is good for a "days of the raj" style escape from the hecticness of Asia: terrace bar overlooking the river.
Don't know if it's still there but there used to be a place called Happy Pizza just round the corner from FCC: you could order a pizza and then for an extra dollar, they'd make it into a happy pizza by throwing a handful of cannabis on to it. I'm not into drugs at all, but, you know, when in Rome... Made the trip back to the hostel on the back of a motorcycle taxi more memorable.
It's a fascinating country, although I think my interest in it is due to how easily a country can succumb to the excesses of lunatics like Pol Pot. There was times when it seemed like the whole country, or at least the older people, were suffering from a collective PTSD, but then you see the young kids playing with their home made kites in the park.