For the Sour Cream Crust:
For the Filling:
Prepare the crust.
Process Dough: In a food processor, pulse flour, sugar, and salt (about 5 seconds). Add frozen butter and pulse until it resembles coarse meal, with butter pieces no larger than peas (about 10 pulses).
Add Liquids: Mix sour cream and ice water in a bowl. Add to the flour mixture and pulse until the dough forms clumps and no dry flour remains (about 12 pulses).
Chill: Form dough into a 4-inch disk, wrap in plastic, and refrigerate for 1 hour.
Roll and Shape: On a floured surface, roll dough into a 12-inch circle. Place in a 9-inch pie plate, trimming to leave a ½-inch overhang. Tuck the overhang under and press against the rim, then chill the shell for 30 minutes.
Prepare the Filling and Bake:
Preheat: Preheat oven to 375°F (190°C).
Make Filling: Melt 8 tablespoons butter in a saucepan over medium heat. Whisk in brown sugar, flour, nutmeg, allspice, and ½ teaspoon salt. Remove from heat and whisk in egg yolks, heavy cream, and cider vinegar.
Assemble: Place raisins, dates, and pecans in the bottom of the chilled pie shell. Pour the cream mixture over the fruit/nut mixture.
Bake: Bake until the filling is set and the crust is golden brown, about 35 to 45 minutes.
Cool: Let the pie cool completely, at least 4 hours, to allow the custard to set properly.
