For radicchio salad with oranges, first cut the radicchio into noodles and soak in warm water to dissolve some of the bitterness.
Cut the orange in half. Squeeze one half, peel the other half and cut it into pieces. Now mix well the sour cream with the orange juice, the orange pieces, oil, vinegar and the soy sauce. Spin the radicchio dry and mix with the marinade.
Let it marinate for a few minutes and serve the radicchio salad with oranges.