Suffering from a jones for poppy-seed bread, I stopped into my local Turkish food market and asked for poppy seeds to grind. The guy told me to try "haşhas," a Turkish poppy-seed paste. I'm glad to have taken his advice.
Hashas is a richer brown than the usual store-bought poppy-seed paste. It's also not quite as sweet. It worked quite well for putting together this sourdough babka flavored with walnuts.