To make the fruit filling, mash the banana and pop into a bowl with all the ingredients. Mix well and leave covered in the fridge overnight for the flavours to develop.
To make the pastry, mix all the dry ingredients together in a large bowl. Cube the butter, then use your fingers to rub it in to form breadcrumbs. Split the vanilla pod and scrape in the seeds. Grate in the lemon or orange zest, then mix in the sugar.
Add 2 tablespoons cold water to the mix, then quickly and gently work it into a dough. Wrap in clingfilm and chill in the fridge for 30 minutes.
Remove the pastry from the fridge. Place a large sheet of greaseproof paper in front of you, put the chilled dough on top, place another sheet on top and thinly roll out the pastry (this will stop you needing any more flour).
Preheat the oven to 180°C/350°F/gas 4, grease your pie tin well and take the fruit filling out of the fridge. Cut out 12 pastry circles, big enough for your tin and 12 star lids (if you don’t have a star cutter, just make round lids).
Place a round in each of the pie moulds, before filling with the fruit and topping with a lid. Brush with a little milk to help them colour.
Bake for 15 to 20 minutes, until golden. Allow to cool before taking out of the tins. Once completely cooled, dust with icing sugar.
This recipe will give you enough filling for 16 pies, so store leftovers in a jar for up to a week in the fridge for a fresh batch later.