Halve the avocados, carefully remove the pulp from the skin and cut into slices. Peel the oranges so that the white skin is also removed and fillet them. Catch the dripping fruit juice for the marinade. Cut the mozzarella into thin slices. Arrange all ingredients alternately on a plate.
Prepare a marinade from vinegar, oil, the collected orange juice, pepper, salt and sugar, season to taste and pour over the salad.