Whiz the beetroot in a food processor until fine. Set aside in a bowl.
In the food processor, pulse the flour, butter, icing sugar and salt until they resemble fine breadcrumbs. Add the beetroot and pulse to combine. Add the cold water, a tablespoon at a time until the dough comes together in a ball. You don’t want it too wet.
Press the dough into a flat disc shape, to aid rolling later, cover in clingfilm and refrigerate for at least half an hour or even overnight.
Lightly grease a bun or muffin tray. Preheat oven to 190C/375F.
Take half of the dough from the fridge and roll it out thinly. Cut circles slightly larger than the holes in the tray using a cookie cutter or the edge of a glass. Cut out shapes, such as stars, to top the mince pies. Gently press the circles into the tray, fill ¾ full with the mincemeat and top with the star shaped pastry.
Bake for 10 minutes or until they just begin to brown. Remove from the tray and cool on a wire rack. When the tray is cool, repeat with the remaining pastry.