8 tbsp unsalted butter – cold, cut into 0.5-inch cubes
4 tbsp ice water
1.5 pounds strawberries – hulled and sliced 0.5-inch thick
0.5 cups granulated sugar
3 tbsp cornstarch
1 tbsp lemon juice
all-purpose flour – for dusting
1 egg – beaten (for egg wash)
1 tbsp water – for egg wash
1 tbsp coarse sugar – for sprinkling
Instructions
Whisk the flour and salt in a large bowl. Cut in the cold butter with a pastry cutter or fingertips until pea-sized bits remain.
Sprinkle in the ice water, 1 tbsp at a time, tossing with a fork until the dough just comes together; press into a 6-inch disk. Wrap and chill until firm, about 1 hour.
Meanwhile, combine the strawberries, granulated sugar, cornstarch, and lemon juice in a bowl. Gently toss and let stand 10 minutes to start releasing juices.
Heat the oven to 400°F (200°C). Line a rimmed baking sheet with parchment paper.
Lightly flour a sheet of parchment (for dusting). Roll the dough on it to a 12-inch round, about 1/8 inch thick. Slide the parchment with the dough onto the prepared baking sheet.
Spoon the strawberry filling onto the center of the dough, leaving a 2-inch border; include some juices but not all if very runny.
Fold the border up over the fruit, pleating as needed. Beat the egg with the 1 tbsp water, then brush the crust with the egg wash. Sprinkle the crust with the coarse sugar.
Chill the assembled galette on the baking sheet for 10 minutes to firm the dough.
Bake until the crust is deep golden and the filling is bubbling thickly in the center, 35–45 minutes; rotate the pan halfway through. If the crust browns too fast, tent the edges loosely with foil.
Cool on the sheet for 20–30 minutes so the juices set. Slice and serve warm or at room temperature.