1. Whisk flour, sugar, and salt in a bowl.

2. Cut in cold butter until pea-sized pieces remain.

3. Stir in sourdough discard and enough cold water until dough comes together.

4. Shape dough into a disk, wrap, and refrigerate for 1 hour.

5. Toss apples, cranberries, brown sugar, cinnamon, cornstarch, and lemon juice in a bowl.

6. Let fruit mixture sit for 10 minutes to release excess juice.

7. Roll chilled dough into a 12-inch circle on a floured surface.

8. Transfer dough to parchment paper and add fruit filling, leaving a 1.5-inch border.

9. Fold edges of dough over filling, pleating as needed.

10. Chill assembled galette on a baking sheet for 20 minutes.

11. Preheat oven to 400°F (200°C).

12. Brush crust with egg wash and sprinkle with raw sugar.

13. Bake for 35-40 minutes until crust is golden and fruit is bubbling.

14. Let galette rest for 15 minutes before slicing.