Pickled herring (or green herring) is young (not yet fertile) herring that is put into brine and left there to ripen for a bit. These are often prepared "nach Hausfrauenart" (housewife's style), which is in a thick creamy sauce together with apples, onions and pickled cucumbers and usually eaten together with potatoes. I really love this dish, and since the fishmonger at the market in our town sells brined trout (which, taste-wise, is very close to pickled herring), I get to enjoy this more often these days.
It does not look spectacular...
...but oh, the tastes and textures!
To serve one to two persons, depending on how hungry you are (and if you serve it with potatoes or not):
~150 g brined herring (or other brined fish), filleted
about the same amounts apple, pickled cucumber, and onion
Cut the onion into rings (traditional) or dice it finely (I prefer that). I like to marinate the cut onion for a bit in a splash of the pickling liquid from the cucumbers, but that's optional. Cut the cucumbers into pieces (I dice everything!), peel the apples and also cut them up.
Traditionally, you now add a mixture of sour cream, cream and maybe even mayonnaise (you want a thick creamy consistency in the sauce), mix that with the apples, cucumber and onion, insert your brined fish and let it stand at least for a few hours, overnight is even better, for the flavours to mix and develop. It's usually quite a lot of sauce, much more than I used for the version in the photo. You won't be needing salt for this, as the brined fish is salty itself (in some cases, it's even recommended to soak it in water first to remove some of the salt), but an absolutely necessary herb for this is dill - so do add some, at least, up to a generous amount, or it won't be what it is supposed to be.
I prefer preparing this dish as a kind of salad, so I dice the fish up as well and go easier on the sauce amount. I've also recently discovered skyr, which is a traditional Icelandic dairy thing somewhere between curd cheese and yoghurt. It is fairly thick in consistency, has a lot of protein and little fat, and also works wonderfully as a sauce for this. For the salad in the picture, I added about 150 g of skyr - so it's basically about equal amounts of each ingredient (except the dill, that would be overdoing it). With the splash of pickling liquid that I marinated the onions in, the skyr ended up the perfect sauce consistency.
The result? The apple, cucumber and fish pieces are all sour, but each in its own way, and they have distinctly different textures. The onion adds some zing to the dish, and a fourth texture, while the dairy envelops all of these and lends a rich creamy mouthfeel to the whole thing. I will eat this straight, with a spoon, no need for potatoes, and be utterly ridiculously happy.
Obviously, you can adapt the amounts of the individual ingredients if you prefer more apples, or no onions, or whatever. (There's even a version where the apple is replaced by pineapple, though I'm not really fond of that.) If you're serving it with potatoes, it's advisable to make some more cream sauce, as that goes really well with the 'taters and it will be a little dry otherwise.
If you can get brined herring, feel adventurous, and do try this dish - let me know if you liked it. I hope you will!