Heilongjiang Restaurant
Popular Chinese option, which also serves a bit of Russian cuisine. Live music in the evenings from 21 Tu-Su. Unlike to stir much excitement, but it's not bad either if you avoid the deep-friend-greasy stuff.
Suin Restaurant
Interesting, if upscale and slightly expensive option, as they besides some usual suspects from the Russian and European kitchens, had a few traditional Nanai dishes on the menu at the latest visit.
Sushi City
For a frontier restaurant rather fancy and modern decór, obviously sells Sushi and other usual suspects of the Japanese kitchen. Also has take-away which is a nice concept for the train journey don't you think? though, if you're a regular at high-class sushi joint's back home, you might want to give it a miss.
Golden Buddha Cafe
Aside from a selection of Chinese cuisine, this place offers excellent Green Tea, and more importantly a wide variety of cocktails and other alchohol. Sometimes have live music, though it's mainly "restaurant style" table seating, so best for groups.
As the author of the Lonely Planet guide so eloquently puts it; "Komsomolsk isn't Russian for 'spirited dining scene'"...