Oh, there's so much to choose from. Cabbage and vine leaf sarmas, beans, lentils (which, to my utter disbelief, we now import from Canada), kavarma, kapama, the stuffed peppers mentioned above (which I hate, but they're as Bulgarian as you can get), my favorite shkembe chorba and so on...
Here's an easy one. It has several variations and most are called Яйца по панагюрски, I just call it eggs with cheese. You boil some water then drop a couple of eggs in it (without the shells, I mean). You crumble some cheese or cut it in cubes in a dish. After the eggs are white and boiled (with still liquid yolks), take them out and put them on the cheese. In a pan with some oil or ideally butter, you fry some of paprika, then pour it on the eggs. Ta-daa!
And if you watn something more challenging, I have a fantastic recipe for a cake, that even my grandmother doesn't remember where she got it from. I'll translate it for you if you want. :)
And here's an idea for your next challenge - make several types of зимнина. Not in February, though.