Place the berries in a bowl, sprinkle with the sugar and liqueur and leave them to them to marinate. Place in a bowl the egg yolks, vinsanto and sugar, mix and place over a sauce pan with just simmering water. Whisk continuously for about 3-4 minutes or until very fluffy and creamy. Take off the heat. Put some of berries in the vol-au-vents pour the zabaione over it a little to the side, sprinkle the rest of the berries on the plate and decorate with a dusting of icing sugar.