Mincemeat: Place all the ingredients in a large Dutch oven, and bring to a boil over medium heat, stirring often. Then, reduce the heat to medium-low and simmer the mincemeat, stirring often, for about 25-30 minutes, or until the liquid is almost evaporated. Transfer the mincemeat to a large bowl and let it cool completely. Cover with plastic wrap and place in the refrigerator, at least overnight, or up to a month. Note: If storing longer than a week, stir in a little rum or brandy (about 1/4 cup (60 ml)) every week. Note: Since you only need 3 cups of mincemeat for this tart, you will have 3 cups left over for another use.

Pate Brisee:  In a food processor, place the flour, salt, and sugar and process until combined. Add the butter and process until the mixture resembles coarse meal (about 15 seconds). Pour 1/4 cup (60 ml) water in a slow, steady stream, through the feed tube until the dough just holds together when pinched. If necessary, add more water. Do not process more than 30 seconds.

Turn the dough onto your work surface and gather into a ball. Divide the pastry in half, flatten each half into a disk, cover with plastic wrap, and refrigerate for 30 minutes to one hour before using. This will chill the butter and relax the gluten in the flour. 

Mincemeat Tart:  Preheat the oven to 375 degrees F (190 degree C) and place oven rack in the center of the oven. Butter, or spray with a non-stick vegetable spray, one - 8 or 9 inch (20-23 cm) tart pan. Place the tart pan on a larger baking sheet.

Remove one round of pastry and on a lightly floured surface, roll the pastry into a 1/8-inch (3 mm) thick circle. To make sure the pastry is large enough, take your tart pan, flip it over, and place it on the rolled out pastry. The pastry should be about two inches larger than the pan. To prevent the pastry from sticking to the counter and to ensure uniform thickness, keep lifting up and turning the pastry a quarter turn as you roll (always roll from the center of the pastry outwards to get uniform thickness).    

When the pastry is rolled to the desired size, lightly roll the pastry around your rolling pin, dusting off any excess flour as you roll. Unroll onto top of tart pan. Never pull the pastry or you will get shrinkage (shrinkage is caused by too much pulling of the pastry when placing it in the pan). Gently lay in pan and with a small floured piece of pastry, lightly press pastry onto the bottom and up the sides of pan. Trim the edges of the pastry so you have about 1/2 inch (6 mm) overhang. Fill the tart shell with 3 cups of the homemade mincemeat and dot with butter.

Then remove the second round of pastry and roll it into a round circle that is about 1/8 inch (3 mm) thick. Using a pizza cutter or fluted edged pastry wheel, cut the pastry into 3/4 inch (2 cm) wide strips. Using an offset spatula gently transfer the strips to the tart pan. Lay the strips, evenly spaced, across the tart and then turn the pan a quarter turn and lay the remaining strips across the first strips so you have a lattice pattern. Seal and trim the edges of the strips to fit the tart pan.

Bake for about 45 minutes or until the pastry has lightly browned.  Remove from oven and place on a wire rack to cool. Serve warm or at room temperature with vanilla ice cream. This tart can be frozen.

Makes 1 - 8 or 9 inch (20 or 23 cm) tart.

Source:

Rodgers, Rick. 'Christmas 101'. William Morrow. New York: 1999.