Preheat oven to 375°. Line large baking sheets with parchment paper.
In a small skillet, heat oil over medium-high heat. Add onion; cook until lightly browned, about 3 minutes. Remove from heat.
On a lightly floured surface, unroll piecrusts. Using a 4½-inch round cutter dipped in flour, cut dough, rerolling scraps as necessary. Brush edges of dough with water. Place about 1 tablespoon brisket onto lower half of one round. Top with about 1 teaspoon onion and 2 teaspoons Cheddar. Fold dough over filling; pinch seams to seal. Place on prepared pan. Repeat with remaining dough, brisket, onion, and Cheddar.
In a small bowl, whisk together egg and 2 teaspoons water. Brush egg wash onto dough, and sprinkle with salt. Prick top of dough once with a fork dipped in flour.
Bake until golden brown, 15 to 17 minutes.
Notes
Kitchen Tip: You can purchase smoked beef brisket from your local barbecue restaurant.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/smoked-brisket-hand-pies-recipe/