1. Get out your 12-hole mini muffin pans along with a 2 ¼- inch fluted, round cookie cutter and a 1 ¾- inch star cutter.
2. Measure the flour into a shallow bowl or dish and, with a teaspoon, dollop little mounds of vegetable shortening into the bowl, add the butter, diced small, shake to cover it, then put in the freezer for 20 minutes. This is what will make the pastry so flaky and tender.
3. Mix together the orange juice and salt in a separate small bowl, cover and leave in the refrigerator to chill.
4. After the 20 minutes, empty the flour and fat into the bowl of your food processor and blitz until you’ve got a pale pile of cake-like crumbs. Pour the salted juice down the funnel, pulsing until it looks as if the dough is about to cohere; you want to stop just before it does (even if some orange juice is left). If all your juice is used up and you need more liquid, add some iced water.
5. If you prefer to use a freestanding mixer to make the pastry, cut the fats into the flour with the paddle, leaving the bowl in the refrigerator to chill down for the 20-minute flour-and-fat-freezer session. Add liquid as above. I often find the pastry uses more liquid in the mixer than the processor.
6. Turn the mixture out of the processor or mixing bowl onto a pastry board or work surface and, using your hands, combine to a dough. Then form into 3 discs (you’ll need to make these in 3 batches, unless you’ve got enough mini muffin pans to make all 36 pies at once).
7. Wrap each disc in plastic wrap and put in the refrigerator to rest for 20 minutes. Preheat the oven to 425°F.
8. Roll out the discs, one at a time, as thinly as you can without exaggerating; in other words, you want a light pastry case, but one sturdy enough to support the dense mincemeat. This is easy-going dough, so you don’t have to pander to it: just get rolling and patch up as you need.
9. Out of each rolled-out disc cut out circles a little wider than the indentations in the tart tins; I use a fluted cookie cutter for this. Press these circles gently into the molds and dollop in a scant teaspoon of mincemeat.
10. Then cut out your stars with your little star-cutter—re-rolling the pastry as necessary—and place the tops lightly on the mincemeat.
11. Put in the oven and bake for 10-15 minutes: keep an eye on them as they really don’t take long and ovens do vary.
12. Remove from the oven, prying out the little pies straightaway and letting the empty tin cool down before you start putting in the pastry for the next batch. Carry on until they’re all done.
13. Dust over some confectioners’ sugar by pushing it through a tea strainer, and serve the pies with one of the butters.