In a pan over medium heat, cook the cold unsalted butter until it becomes browned, watching closely for a nutty aroma and a golden color. Once browned, remove the pan from heat and let the butter chill in the refrigerator until firm.

In a mixing bowl, cut the chilled butter into cubes and combine with all-purpose flour and fine sea salt in a separate bowl.

Work the mixture until it resembles small peas.

Gradually add cold water and apple cider or white vinegar to the flour and butter mixture. Stir gently until the dough begins to clump together.

Divide the dough into two equal portions, form into discs, wrap in plastic wrap, and chill in the refrigerator for at least 30 minutes.

Preheat the oven to 425°F. Roll out one disc of dough on a lightly floured surface until it fits your pie pan, then carefully place it in the pan.

In a bowl, combine the fresh sliced peaches and quartered strawberries, then sprinkle in the granulated sugar, cornstarch, lemon juice, lemon zest, and pinch of fine sea salt. Toss gently.

Pour the fruit mixture into the pie crust, ensuring an even distribution.

Roll out the second disc of dough for a lattice top or simply cover with slits for steam to escape.

Brush the crust with the whisked egg and sprinkle with Turbinado sugar if using.

Bake for 25 minutes at 425°F, then reduce the temperature to 350°F and continue baking for an additional 40-50 minutes until the crust is golden brown and the filling is bubbly.

Allow the pie to cool at room temperature for four hours before serving.