Tomato & Plum Galette with Black Pepper-Parmesan Crust

Name: Tomato & Plum Galette with Black Pepper-Parmesan Crust
Prep time: 25 min
Cook time: 35 min
Total time: 1 h
Cuisine: French
Ingredients: 1 1/4 cups unbleached all-purpose flour; 2 tablespoons finely grated Parmesan; 1/2 teaspoon freshly ground black pepper; 1/2 teaspoon sea salt; 8 tablespoons (1 stick) unsalted butter, cold; 2 tablespoons sour cream, cold; 5 tablespoons ice water, plus more as needed; 3 cups small heirloom tomatoes (I used a mix of cherry, grape, and plum varieties); 1 dash sea salt; 3 medium black plums; 1/4 cup finely grated Parmesan, divided; 1 egg, lightly beaten; 1 dash ground black pepper; 1 tablespoon torn tarragon leaves