Squeeze the citrus fruits, filter the juice and put it into a jug. Gently pour in the sparkling wine, a little at a time, without creating too much froth. Add the saffron pistils and stir. To serve it, put a spoonful of La Fragolina in the bottom of each glass, pour in the cocktail you’ve just prepared and add a sprig of rosemary – which will then be used to mix the ingredients before drinking. 

 (1) To make it at home, blend fresh strawberries with 2-3 tablespoons of sugar.