1. For dough: Pulse to combine flour, sugar, and salt in a food processor fitted with a metal blade. Add shortening and pulse 10 times. Add butter and pulse until mixture resembles coarse meal. Beat egg yolk and vinegar together, add and pulse 3 to 4 times. Remove and gather dough together-if needed sprinkle up to one tablespoon of ice water over dough to bring together. Shape dough into disk and wrap in plastic. Refrigerate1 hour or up to 2 days.

2. For filling: Peel sweet potatoes and mash lightly with a fork. Transfer to food processor with butter and process until smooth. Add remaining ingredients, pulse to combine, and set aside.

3. Roll dough into a 12-inch circle on a floured work surface. Fit into a 9-inch pie pan and trim leaving a 1/2 inch overhang. Fold edges and crimp. Prick dough all over and refrigerate for 20 minutes or up to 1 day.

4. Preheat oven to 425F. Line crust with parchment paper, add pie weights, and place on a baking sheet. Bake until set and brown at edges, about 25 minutes. Remove paper and weights. Reduce oven temperature to 375F. and continue to bake until crust begins to brown on bottom, about 10 to 12 minutes more. Pour filling into warm crust and bake until set, about 20 minutes. Remove from oven and cool on rack

Heat oven to 350 degrees F. Lightly beat egg white until frothy. Whisk in sugar and cinnamon. Toss in pecans and evenly spread nuts on a parchment-lined baking sheet. Bake until dry and toasted, about 10 to 15 minutes. Cool.