Wash the savoy cabbage and blanch in boiling salted water for about 3 minutes. Rinse immediately in cold water. Cut the leaves in half along the leaf panicle, removing the panicle. Mix quark and wasabi.
Season to taste with salt and lemon juice. Wash the salmon, dab dry and cut into thin slices. Place the salmon in the middle of the savoy cabbage leaves and spread 1 teaspoon of wasabi cream on each.
Fold the short sides inwards and roll the savoy cabbage leaves into small rolls and pin them down. Cut mushrooms from the root. Heat the oil and fry the rolls all around for about 4 minutes.
Fry the mushrooms briefly and thoroughly in the frying fat. Season to taste with soy sauce. Remove the needles from the rolls. Arrange rolls and mushrooms on plates.