Pie Crust:
Add flour, sugar, and salt to the bowl of a food processor or mixer fitted with cake paddle. Pulse or mix to combine. Add butter or vegan butter, ice water, and egg yolk and pulse until the dough becomes a ball and holds together.
Flatten dough into a disk, wrap and refrigerate for 1 hour.
Line a baking sheet with parchment paper.
Once dough has chilled, dust your counter top or surface a small amount of flour. Roll dough in a large circle until it’s ¼-inch thick. Brush off excess flour with a pastry brush, then carefully transfer dough to prepared sheet.
Galette:
Preheat oven to 350°F.
Add apples with cornstarch, juice and zest, sugar, cinnamon, and salt to a large bowl and toss all ingredients together.
Place apples on rolled dough, leaving 2-inches around the edges without filling.
Fold edges toward the center, allowing the dough to fall into pleats. There will be an opening in the center where the steam escapes and the filling peeks through.
Brush dough with egg wash and sprinkle with sugar. This will make the dough shiny and add a bit of crunch to the dough.
Bake in a 350°F oven for 40 to 50 minutes, or until pastry is golden brown and apples are bubbly.
Transfer galette to a platter and drizzle with caramel sauce (optional). Cool slightly, slice, and serve.