In a bowl, combine plain flour, icing sugar, 4 tablespoons shortening and water. Knead to make a dough. In another bowl, knead the cake flour and remaining 5 tablespoons shortening to make another dough.
Wrap the cake flour dough with the plain flour dough and roll out into a 20x40cm sheet. Fold 3 times.
Roll out into a sausage about 3cm thick, then flatten to make a strip 10x80cm. Cut into 10 squares.
In a bowl, mix the BBQ pork with the BBQ sauce. Place a tablespoon of filling on each pastry piece, wet the edges with egg yolk and roll up, sealing the ends. Brush each pastry with egg yolk and sprinkle with sesame seeds.
Bake on greased baking trays 25 minutes or until crisp and golden. Serve hot or warm.