I hope you got to read up Bulgaria city break piece and some the reviews of the restaurants I visited. Here is a round-up of some other places which are definitely worth a visit during your Sofia trip. (Main picture is Cigar bar from Hotel Marinela).
Decanter – Ulista Profesor Assen Zlatarov 15
A sweet and informal residential bistro with a fine selection of wines to buy or drink on site. They also do plates with selections of their own cheeses as well as the most amazing tomatoes that burst with flavour.
Oscar Club, 15 Slavyanska Str, 1000
A cool bar with one of the best cocktail lists I had seen in Sofia. They have an extensive list, but also have great knowledge to order items that are not on the menu.