Peel oranges so that the white skin is completely removed. Remove the fillets with a sharp knife between the parting skins. Squeeze the juice out of the parting skins and collect it. Cut the fillets into pieces.
Peel the carrot and cut into pieces. Cut the mango from the stone. Peel and chop the flesh. Clean and wash the watercress and let it drain well in a sieve.
Oranges, collected orange juice, carrot, mango, apple juice and watercress, except for a few stems for garnishing, place in a blender and mix. Pour into glasses, garnish with watercress and serve immediately.