Peel 3 oranges, also carefully remove the white skin. Separate the fillets. Cut 500 g cleaned strawberries crosswise into slices. Put both in a punch bowl. Pour 200 ml orange juice through a sieve, stir with 2 tablespoons of powdered sugar until smooth, pour over the fruit. Cover and chill for 20 minutes. Fill up with cold white wine and cold prosecco before serving.