in nearly every serbian restaurant you can get grilles mushrooms w/ olive oil and/or "serbian salad" - both are yummy yummy, i didn't eat anything else while i stayed in belgrade for 10 days. anyway: not the perfect country for vegans ;-)
Thanks. :)
The truth is that Belgrade is not very veg-friendly.But still there are options in non vegan restaurants.I had been in Belgrade last year and I remember that small falafel shop Tel Aviv which is close to Kalemegdan.You will probably find it.It's a cheap and rather convenient solution if you don't wish to spend much time in a restaurant.There is also a small take away chinese fast-food restaurant which offers noodles with vegetables (I don't remember the exact name of the stree but I remember that it's on a vertical street of Kneza mihaila-closed on Sundays though!).I hope I helped you a little bit.Enjoy your stay in BG!
