Hien Nam was doing a good trade at lunchtime when we visited which you can take as an indication they're doing com dia right! I guess the price (15,000 VND) is a draw card too.
As the last reviewer noted, the staff just put food down in front of you. No ordering. But this isn't special treatment for tourists who don't speak Vietnamese, everyone just gets a bit of everything. A few people wandered up and pointed to things they wanted more of, or wanted left if their plate but no one ordered anything, per se.
What arrived on our table was the best food we've had in Vietnam at this style of eatery. First, the soup was really refreshing with tiny cubes of tofu and lots of greens. It tasted citrusy as well as slightly bitter so I'm thinking kafir lime leaves. They brought us iced jasmine tea in glasses which might have been special tourist treatment because everyone else just filled their own plastic cups from a big thermos. All the dishes were just a cut above the other com dia we've eaten - lighter and fresher with more distinct flavours in each dish. I was delighted to see cooked jackfruit on my plate, as well as a bitter melon dish, green mango salad, and other things I can't name or even really describe! But everything was delicious. It was a nice change to have mostly veggies on my plate in great variety with a bit of tofu and just a few pieces of fake meat.
Updated from previous review on Monday March 02, 2015
Cons: served lukewarm - cold but that's what you expect