Soften the potatoes and the beet separately. (potatoes 20-30 min. beet 35 min.) In the meantime, dice the herring fillets and the pickles. Chop the dill. For the sauce, mix yogurt with whipped cream, juice of one lemon and mustard thoroughly. Season with salt, pepper and sugar. Fold in the oil.
Peel and chop the potatoes and beet. Mix with the remaining ingredients and the sauce.
Tip: Use a normal or light yogurt as needed!