First make the mincemeat (if you don't have any): Peel and grate the apple. Put the sugar and apple juice in a large pan and heat it up. When the sugar has dissolved, add the grated apple and all other ingredients except vanilla, nuts and orange liqueur. Cook for 20-30 minutes until the fruits are soft and sauce becomes thick and sticky. Turn off the heat and add the remaining ingredients. Stir well, then transfer to a jar.
Sift the flour, cornmeal and salt into a bowl. Dice the butter and rub it into the flour with your fingers. When it resembles breadcrumbs add the egg and, using a palette knife, combine it into a dough. Knead it into a ball, wrap in cling film and chill until needed or at least 30 minutes.
Preheat the oven to 180°C.
Put the ball onto a lightly floured cold surface ( use rice flour!) then roll out the pastry to 3mm thickness - use a sheet of clingfilm under the rolling pin if it's too sticky.
Cut out 12 round shapes using a 7/8 cm cutter or a mug. Push these gently into a 12-hole tart or shallow muffin tin. Roll out the leftover pastry again and cut out more rounds or star shapes.
Fill the tarts with mincemeat, then cover them with the pastry shapes. Seal the pastry edges together. If you're using rounds,cut two little holes in the top to allow the steam to escape.
Bake for about 20 minutes.
Serve lukewarm with icing sugar dusted over them.