Preheat the oven to 190°C. Line a baking tray with parchment paper
Unroll the pastry and cut in into approx. 10x10 cm squares. Spoon some mincemeat mixture into the middle of each square then fold the pastry diagonally to form triangles. Using a fork or your fingers, seal the edges by pressing them together. Cut an insertion on the top (or star shape) to allow the steam to escape.
Put them on the sheet, then brush them with the egg or milk.
Bake for about 15-20 minutes, until golden.
Let them cool slightly, then dust with icing sugar.
Serve warm or at room temperature.