Essentially, a honey mustard dill sauce however without any honey just a few tablespoons of sugar. In theory, this dish should be quite delicious. However, the sauce isn’t quite perfected. I couldn’t find herring so I substituted with sardines as the book suggests. But honestly, I think salmon would be better than sardines. The one addition that actually did work were the slices of red onion which actually interacted with the flavour of the sauce quite well.