mostly down at the promenade that heads along the beach you'll find a lot of people who sell hot sweetcorn. it's very cheap and tasty! But there are other great possibilities to eat local food. one restaurant sells kind of russian souvlaki (can't remember the name). You can try everything because it's very cheap!
There are various cafes etc. around. If eating outside beware of the wasps. I was eating in a stolovaya (self-service restaurant) and because of the massive wasp attack had to flee back inside. A local woman told me that wasps had been especially bad this year.