I had never head of Charnushka or Nigella seeds until ITJB so, being the curious type, I ordered some ... and now I'm hooked!
What a wonderful surprise. These little seeds that look like undersized black sesame taste of black pepper, thyme, onion and I don't know what else. They are wonderful on top of rolls. I got some cheaply from www.myspicesage.com but I'm sure other places like Penzey's have them.
Glue them on with egg wash and it's a great way to perk up a plain chewy roll.