Tomato Pie With Sour Cream Crust

Name: Tomato Pie With Sour Cream Crust
Ingredients: 2 cups all-purpose flour, plus a little extra for dusting; ½ teaspoon salt; 2 teaspoons dried parsley; 13 tablespoons (1 stick plus 5 tablespoons) cold unsalted butter, diced; 6 tablespoons sour cream or plain full-fat yogurt; 1 tablespoon white wine vinegar; ¼ cup ice water; 2 tablespoons cooking fat; 1 large onion, thinly sliced; 2¼ pounds mixed heirloom tomatoes (mix of full size and cherries); ¾ cup hard salty cheese, such as Manchego or Parmesan; ¾ cup shredded mozzarella cheese; ¼ cup mayonnaise; 3 tablespoons chopped basil leaves; 3 tablespoons chopped parsley; 1 teaspoon chopped thyme; Salt and freshly ground black pepper; 1 egg, beaten; 1 tablespoon milk, cream, or water