Put a few pretty raspberries aside for garnish. In a bowl combine the rest of the raspberries with icing sugar and set aside for 30 minutes. Press raspberries through a sieve and discard the seeds.
Pour orange juice into a small saucepan, sprinkle gelatine on top and let soak for 1 minute. Heat liquid over low heat, until gelatine has dissolved completely, but do not bring to the boil.
Take the pan off the heat, leave to cool for a few minutes and mix with raspberry puree.
Mix the cream and vanilla sugar in a big bowl and beat until stiff. Fold into the raspberry puree. Add lemon juice and more icing sugar to taste, cover with cling film and place in the fridge for about 2 hours. Garnish with raspberries and serve.
Vanilla sugar is generally available in supermarkets nowadays, however, in a pinch substitute 1 teaspoon of vanilla extract to every 2 teaspoons vanilla sugar.