Start this recipe by cooking together the apples, sugar and orange zest for 5 minutes to soften the apples. Add in the strawberries and berries and cook for just 2 minutes. Allow to cool before mixing in the cold custard and a handful of cake crumbs. Take the vanilla sponge and cut half into 1cm thick slices. Crumble the remaining half into crumbs. Place the rolled puff pastry sheet onto your work top and place the sliced sponge down the middle of the puff pastry. Carefully spoon the apple and berry filling on top of the sponge (this will prevent any juices from making the puff pastry soggy during cooking) and cut the excess pastry on both sides into 2cm strips horizontally, but still keep them attached to the center. Next, start to fold the pastry strips alternatively over the mincemeat filling, from one side to another, like a plait. Place the strudel on a greased baking sheet, brush with a little water and sprinkle over the flaked almonds. Bake in the oven at 200`c for about 25-30 minutes, or until the pastry is golden brown and crispy. Remove the puff pastry strudel from the oven and allow to cool down for 10 minutes. Carefully lift the strudel onto a long serving plate, dust with icing sugar and serve. The apple and berry puff pastry strudel can be served either hot or cold, sliced into thick portions.