Clean and wash spring onions and cut into rings or strips. Put something aside for garnishing. Mix curd, except for 1 tablespoon, spring onions and 1 tablespoon of oil. Season with salt, pepper and some sugar.
Drain the sauerkraut on a sieve. Peel, wash and roughly grate the potatoes. Squeeze the sauerkraut. Stir egg, sauerkraut, 1 tablespoon curd and starch into the potato mixture. Season with salt, pepper and a little nutmeg.
Heat 2-3 tablespoons of oil in a frying pan. Squeeze the potato mixture vigorously. Shape 16 portions of the mixture in the pan and fry on both sides at medium heat. Arrange the Röstis and quark on plates, garnish with parsley and the remaining spring onions.