Make the galette dough:

1. Combine the flour, sugar, and salt in a large bowl.
2. Cut in the cubed butter with a pastry cutter until mostly pea-sized pieces of remain. You can also use a food processor and pulse a few times until combined. Do not over mix.
3. Sprinkle the ice water over the flour mixture 1-2 tablespoons at a time and stir with a butter knife to distribute. Mix the mixture with your hands until it starts to come together in a coarse ball. Sprinkle the dry bits with more water and bring together into a ball.
4. Divide the dough into four equal balls. Wrap the dough in plastic wrap and refrigerate for at least one hour, up to overnight.

Make the strawberry filling:

1. Toss the strawberries, sugar, cornstarch, salt, lemon zest and vanilla bean seeds in a medium sized bowl and let sit for at least 15 minutes.  The berries will release juice which will keep your galette from being watery.

Assemble the strawberry galette:

1. Roll a ball of galette dough onto a floured surface into 8-inch rounds. Transfer to a parchment paper-lined baking sheet.
2. Taking care to leave any released liquid behind, place 1/4 of the strawberry mixture in the center of the flattened dough, leaving 1 inch on each side. Gently fold up the crust over part of the strawberries in an overlapping fashion. Repeat with the other dough rounds.
3. Whisk the egg white and water and brush liberally on the galette crust. Sprinkle with raw sugar.
4. Bake at 400° F for 35 to 45 minutes until crust is golden brown. Serve warm or at room temperature.