By hand: In a large bowl, combine the flour with cornmeal, salt, and sugar. Add the butter, and using a pastry cutter, cut the butter into the flour mixture until it resembles coarse sand. Gradually add the ice water, a tablespoon at a time, until the dough comes together but is not wet.
Using a food processor: Combine the dry ingredients in the food processor. Add the butter and pulse 10 to 12 times until the mixture resembles coarse sand. Gradually add the ice water (one tablespoon at a time); you may not need all of it. The dough should come together but remain a bit crumbly.
Over plastic wrap, shape the dough into a flat disk and chill in the fridge for 30 minutes to up to an hour. This rest period allows the gluten to relax, making it easier to roll out later.
Preheat your oven to 400°F (200°C). The oven should be hot when the galette goes in, ensuring a nice, crispy crust.
Between two pieces of parchment paper, roll out the dough into a 12-inch circle. This rustic shape is part of the galette charm! Aim for a thickness of about an eighth of an inch.
To make the filling, combine the sliced strawberries in a bowl with the sugar, lemon juice, and cornstarch. Toss gently to coat the strawberries evenly. This mixture will create a juicy filling.
Transfer the rolled-out dough to a baking sheet lined with parchment paper. Place the prepared filling in the center of the dough, leaving a 2 to 2.5-inch border. This space will be folded over the filling.
Fold the edges of the dough over the filling, creating a rustic edge. Don’t worry about perfection; that’s the beauty of a galette.
Brush the exposed edges of the crust with the egg wash (the mixed egg with 1 teaspoon of water) for a beautiful golden brown color. Sprinkle with additional sugar if desired.
Bake in the preheated oven until the pie crust is deep golden brown, about 30 to 35 minutes. The filling should be bubbly and fragrant.
Transfer the galette to a wire rack to cool completely. This helps set the filling and makes it easier to cut.
Mix the strawberry jam with the water and carefully brush the glaze over the strawberries. The filling will be soft, so do this step gently.
Serve the galette warm with a scoop of vanilla ice cream, whipped cream, or simply on its own. Each bite is a taste of spring!
