Start by making the pastry. Add the flour, salt, and sugar to a food processor and pulse and few times to blend everything together.
Add in the cubed cold butter and pulse until the butter is pea and lima bean-sized. Add the bourbon and water and mix just enough so it lightly comes together. It will still look loose but will stick together when you squeeze a chunk of it in your fist.
Pour the dough out onto a well-floured surface and form it into a loose disk. Wrap in plastic wrap, and chill for at least 1 hour.
While the dough is chilling, start your filling.
In a medium bowl, toss together the lemon juice, apples, pears, sugar, cinnamon, cornstarch, and cardamom.
Preheat the oven to 400 degrees.
Assemble the galette. On a floured piece of parchment paper, roll the crust 1/8 inch thick and about 12 inches in diameter. Using a pastry cutter or a knife, trim the edges so that it forms a circle.
Place the apples and pears in a circular pattern around the pastry, leaving a one-inch border. Once filled, carefully lift the edges of the pastry and fold it over the fruit filling.
Brush the egg wash over the crust, then sprinkle with sugar.
Place the galette with the parchment paper on a baking sheet with a bake for 45 minutes.
Notes
TRICKS FOR THE PERFECT PIE CRUST:
Keep all the ingredients cold. The cold butter in the pie crust is what makes all those nice layers in the pastry.
Don't overwork the dough. The less you work the dough, the more flakey and crumbly it will be.
Use the good fatty butter. My favorite for pastry is Kerry Gold.
Chill, but don't freeze the dough. The goal is to make sure that the butter is nice and firm but that the dough is still workable.