Make the mincemeat filling: Combine all ingredients in a food processorand pulse 8 to 10 times. Place in an airtight container and store in the refrigerator for at least 3 days or up to 6 months before using. If you prefer a finer texture, place the apples, dried fruit, and suet into a meat grinder with a large die and grind. Transfer to a bowl and stir in the remaining ingredients. You may also finely chop the apples, dried fruit, and suet by hand.
Make the crust: Whisk together the flour, cornmeal, sugar, and salt in a large mixing bowl. Grate the cold butter on the large side of a box grater directly into the dry ingredients. Work together with your hands until the mixture is crumbly. Add the cider and water and stir with a spatula to combine. Knead the dough 5 to 6 times and spritz with additional water if the dough is dry. Shape into a disk, wrap in plastic wrap, and place in the refrigerator for 20 minutes.
To assemble: Heat oven to 400ºF.
Unwrap the dough and divide into 4 equal pieces. Place 2 pieces of dough onto a piece of parchment paper, and roll each out to a 1/8-inch thick round that is 6 to 8 inches in diameter. Spoon about 1/2 cup of the mincemeat into the center of each round, and fold up the edges of the dough to form a crust all the way around. Brush the edges of the crust with egg wash and sprinkle lightly with sugar. Transfer the dough on the parchment to a half-sheet pan. Place on the middle rack of the oven and bake until the crust is golden brown, about 30 minutes. Repeat with the remaining dough.
If you prefer one large pie, roll out the dough on a piece of parchment paper to a 15- to 16-inch round, about 1/4- to 1/8-inch thick. Trim the edges with a pizza cutter. Carefully slide the dough, still on the parchment paper, onto an upside-down half-sheet pan. Spoon about 1 1/2 pounds of the mincemeat onto the center of the dough, leaving a 2- to 3-inch margin around the edge of the crust. Place in the oven and bake until the crust is golden, about 35 minutes. Remove from the oven and cool for 30 to 45 minutes before serving.