Mix the salt and the flour; blend the shortening in; add just enough cold water (a few tablespoons at a time) to get the dough to form a ball. (To be clear, don't add all the water if it is not all needed.) Once the water has been added, you run the risk of gluten developing and making the crust tough, so handle it no more than necessary and above all don't knead it.
Set aside one-third of the dough for the tart lids.
Start heating oven to 200 C / 400 F.
Roll out the other two-thirds of the dough, use it to line 8 of the cups in an ungreased, unheated tart pan.
Put two tablespoons of the mince meat pie filling in each tart.
Roll out the remaining one-third of the pie dough. Cut it into circular lids for the tarts, and apply them.
Brush tart tops with a bit of beaten egg, egg sub or milk for a browner colour [optional].
When oven has fully heated, place tarts in oven and bake for approximately 20 minutes.
Remove pan from oven.
Leave tarts to cool in the tin for 5 minutes, then remove to a wire rack to finish cooling.