Cut out the thick stalk from the savoy cabbage leaves, wash the leaves well, drain them and cut into fine strips. If you want, you can also briefly blanch the savoy cabbage - then it will lose a little of its bitter taste.
Wash apples and oranges well and cut into cubes. Mix the sour cream with lemon juice (or orange juice) and salt and pepper in a larger key, mix with the savoy cabbage strips and the apple and orange pieces and garnish with the walnuts.