Start by making the pastry. Place the plain flour, icing sugar, salt and grated orange zest in a large bowl and stir to combine. Add the cold, diced vegan block butter/margarine.
Rub the butter into the flour using your fingertips until no lumps of butter remain and the mixture resembles coarse sand. You can also blitz it in a food processor if you prefer.
Mix in the cold vodka, then gradually add enough ice cold water to bring the pastry together into a ball. Shape it into a disc (don't knead it!), wrap it well and refrigerate for at least half an hour until firm. At this point it can be kept refrigerated for up to two days.
To make the viennese whirl topping, whisk the softened vegan block butter with an electric mixer until it is very soft indeed, then whisk in the vanilla extract.
Sift in the plain flour, cornflour and icing sugar. Stir with a spatula until it is mixed in then continue to whisk with the electric mixer until you have a smooth, pipeable paste. It should be a stiff buttercream consistency.
If it is too firm it means that the butter is too cold so pop the bowl in a warm spot for a bit then whisk again.
Transfer the mixture to a piping bag fitted with a large star nozzle. Lightly grease a 12 hole mince pie tin/ bun tin.
Thinly roll out the chilled pastry on a lightly floured surface. Use a 7cm (2 ¾in) round cutter to cut out 12 discs of pastry and press them into the bun tin. (The exact size of cutter you need may vary depending on your tin).
Fill each pastry case with a heaped teaspoon of mincemeat. Don’t overfill them as they will boil over.
Pipe a swirl of the viennese whirl topping on top of each one. Don’t go right up to the edge as it will spread a bit in the oven. If the mixture is hard to pipe, use the warmth of your hands to warm up the piping bag to soften it.
Place the tray of mince pies in the fridge for at least half an hour until the topping is firm. This helps the swirls hold their shape in the oven so don’t skip it. Meanwhile preheat the oven to 200°C/180°C fan/400°F/gas mark 6.
Bake the chilled mince pies for about 20 minutes until they are pale golden.
Leave them to cool in the tin for 10 minutes then carefully transfer them to a wire rack to cool completely. You may need to use a knife to loosen any boiled over mincemeat so they don’t get stuck in the tin.
Once the mince pies have cooled, dust them with icing sugar before serving.