Mix the apples with all the other ingredients up to and including the lemon juice.
Carefully unfold the pastry sheets, brush with a little butter and stack all the pastry sheets on top of each other on a tea towel. Spread the filling over the bottom third of the pastry, leaving a gap of approx. 3 cm along the sides, fold the pastry ends inwards. Loosely roll up the strudel, using the tea towel to help you. Place it seam-side down on a baking tray lined with baking paper, brush with a little butter.
Approx. 30 mins. in the lower half of an oven preheated to 200°C. Brush the strudel with the remaining butter several times during baking. Remove from the oven, allow to cool a little, then dust with icing sugar.