Tomato Salad with Feta Cheese

Late one evening in Washington, D.C., after a grueling day on a book tour, I sat back in my room at the Jefferson Hotel and ordered room service. I was obligingly served by Kiril Mitov, a young Bulgarian putting himself through school by working the swing shift at the hotel. We got to talking about books and barbecue, and soon he was telling me about cookouts in Sofia. No Bulgarian barbecue would be complete without this salad, he said, which takes its name from a rural region outside Sofia