Wash and drain the blueberries, currants and strawberries. Sort the raspberries and cut them in half. Carefully strip the currants from the panicles. Clean and chop the strawberries. Puree 200 g strawberries and 20 g sugar, pass through a fine sieve. Mix berries and puree and chill
Soak gelatine in cold water. Bring milk, butter and 60 g sugar to the boil. Stir in semolina and let it simmer for about 2 minutes at low heat, stirring continuously, then remove from the heat. Squeeze the gelatine well and dissolve in the hot semolina. Wash the lemon with hot water, rub dry.
Peel the zest in thin strips with a zest ripper, chop coarsely, add to the semolina. Pour the mixture into a bowl, place on a cold water bath and allow to cool to room temperature while stirring. Whip the cream until stiff and fold into the semolina. Layer mousse and compote alternately in glasses. Chill for about 2 hours.