If you like beans then my vote is for bob chorba (bean soup). I had it when I visited BG and thought it was delicious. My future mother-in-law even sent me home with a bag of Smilyanski beans because I raved about her bob chorba, but I haven't gotten around to using them yet. 

I found a couple recipes for it, but this one seemed straightforward:
http://www.findbgfood.com/bgmeals-favorites-soups.htm#Bob_chorba

The monastery style version looks great too!

Good luck with your project!