Phnom Penh is probably CĂ´tes-des-Neiges' best kept secret and has been open for over 20 years. Having lived in Toronto and Seattle, I make a point to come to Phnom Penh anytime I'm back in Montreal, haven't found any other restaurant like it in other cities!
The go-to for me is definitely the white noodle Phnom Penh soup served as 'kho', which is served with noodles and broth separate with some great garnishes and sauce on the noodles. It's delicious! Coupled with fried chinese bread to dip in the broth, you're in for a treat, get the spring rolls if you're real hungry as well, they're excellent.
One bonus is that despite their restricted hours, they're usually always open on holidays, I've gone numerous times for lunch on Christmas eves and thanksgivings. Oh, and make sure to bring cash!