Pickled Herring with Apple-Potato Salad
Rinse the potatoes and cook in a pot of boiling salted water until knife-tender, about 25 minutes.
For the sauce: Peel the onion and chop finely. Peel and quarter the apples, remove the core and thinly slice. Transfer the apple slices to a bowl and add the sour cream, yogurt and onion and season with salt and pepper. Heat the butter in a skillet. Drain the potatoes, peel, and saute until heated through. Sprinkle with parsley. Drain the herring. Serve the potatoes with the herring and the sauce.