Sift the flour into a freezer-proof bowl and add the vegetable shortening.
Add butter, cover with flour, and freeze for 20 minutes to chill.
Mix orange juice with salt in a separate bowl and chill in the fridge.
Pulse the chilled flour and fats in a food processor until porridge-like crumbs form.
Add chilled juice gradually while pulsing until the dough just begins to come together.
Knead the mixture briefly on a floured surface to form a smooth dough.
Divide the dough into three discs and wrap each in cling film.
Rest the dough discs in the fridge for 20 minutes.
Preheat your oven to 220°C.
Roll out one pastry disc thinly on a floured work surface.
Cut 12 circles using a 5.5cm cutter and press them into the tart tray moulds.
Place 5ml of mincemeat into each pastry case.
Cut out 12 stars from remaining dough and place them on top of the filling.
Bake for 10 to 15 minutes until the pastry turns golden-brown.
Remove pies from the tray immediately to cool on a wire rack and repeat for remaining dough.
Dust the finished pies with icing sugar before serving.