Preheat the oven to 450F (205C).
Start by peeling the persimmon. Using a mandolin, carefully slice the persimmon into thin slices. Be careful here - the persimmon can get slippery.
Place the pie dough on a lined baking tray. Arrange the persimmon in the center of the pie dough. I recommend starting from the center and then working your way outwards.
Once the persimmon has been layered onto the pie dough, sprinkle lemon sugar, cinnamon, and cubed butter on top.
Fold the edges of the pie dough over in sections so it covers the outer layer of the persimmon.
In a small bowl, crack an egg and whisk until homogenized. Brush the edges of the pie dough with the egg wash. Sprinkle raw turbinado sugar on top of the pie dough.
Bake for 40 to 45 minutes or until the crust is golden brown and the persimmon has softened. Brush the crust with the honey ginger syrup, if using.
Allow the galette to rest and cool for 30 minutes. Dust powdered sugar on top before serving and enjoy!