Blueberry Rhubarb Galette

Name: Blueberry Rhubarb Galette
Prep time: 20 min
Cook time: 50 min
Total time: 1 h 10 min
Cuisine: American, French
Ingredients: 1½ cups all purpose flour; 2 tablespoons sugar; ½ teaspoon sea salt; 6 tablespoons cold butter (cut into cubes); ⅓ cup ice water (you may not need all of this); 2 cups blueberries; 2 cups sliced rhubarb; ¾ cup sugar; 2 tablespoons all purpose flour; 2 tablespoons quick cooking tapioca; ¼ teaspoon sea salt; ⅛ teaspoon freshly grated nutmeg; 1 tablespoon lemon juice (~ ½ fresh lemon); 1 large egg (lightly beaten); 1 tablespoon milk; 2 tablespoons sugar (for sprinkling (turbinado sugar is nice here, but granulated works, too))