Combine flour, coconut sugar, salt, coconut oil, and ice water in a food processor, pulsing for about 10-15 seconds, until just barely combined.
Pour onto plastic wrap and cover to form into a disc. Massage it together until it is combined into a dough (while in the plastic wrap, prevents mess!) and then refrigerate while you prep the filling (15-20 mins).
Scoop out the flesh of the hachiya persimmons into a small bowl, and discard the peel. Set aside.
Remove the stem out of the fuyus, wash, and slice into rounds, about 1/8″ thick. Remove any seeds. Place into a bowl and toss with 3 tbs sugar, orange juice and zest, coconut oil, ginger, nutmeg and salt. Try to evenly coat the slices.
Preheat the oven to 400F, line your counter with a sheet of parchment paper (you will directly transfer this to the oven), and remove the dough from the fridge.
Roll the dough out into a circular shape, about 10-12″ wide.* Pour the hachiya flesh in the center, spreading evenly to about 5 cm from the edge, then sprinkle with walnuts and 1 tbs + 1 tsp sugar.
Top the hachiya flash with a concentric circle of fuyu slices, starting from the outside and working in (still leaving a 5 cm edge clear).
Fold up the edges around the fruit, by using the parchment paper under the galette and folding up. This will allow it to be smooth, and prevents mess!
Brunch the outside with the pastry wash, then press coconut into pastry. If the coconut is falling off, you can brush over the coconut with more wash to dampen it up a bit and allow it to stay.
Transfer the parchment paper the galette is already on directly to a baking sheet.
Bake on the middle oven rack for 30-35 minutes, or until the coconut is toasted and persimmons are bubbling.
Dough: Sprinkle water over dough until it stays together if crumbly, and feel free to use you hands rather than a rolling pin to press the dough into a circular shape.