Shortbread Pastry Crust
For pastry: In a large bowl, whisk together flour and powdered sugar. Using a pastry blender or fingers, cut or rub in 1/2 cup butter until mixture resembles coarse crumbs and clings together. (Or, in a food processor, pulse flour and powdered sugar. Add butter. Pulse several times, until mixture clings together.)Advertisement
Press pastry into the sides and bottom of a greased 10-inch fluted tart pan with removable bottom. Prick the bottom of the crust with a fork. Chill for 20 minutes. Preheat oven to 350°.
Bake pastry shell 15 minutes or until very light brown. Cool completely on a wire rack. Remove shell; place on a serving plate.
For filling: In a medium nonreactive saucepan, bring milk and salt to just under a boil over medium heat. Meanwhile, in a medium bowl, whisk together granulated sugar and cornstarch. Add eggs to bowl; whisk until smooth. Gradually whisk 1/2 cup of the warm milk into the egg mixture, then pour egg mixture back into the saucepan. Bring to a gentle boil; reduce heat. Cook and stir for 2 minutes more. Remove from heat. Pour through a fine-mesh sieve into a bowl. Let cool 10 minutes, stirring occasionally. Whisk in the 4 tablespoons butter, 1 tablespoon at a time, followed by the zest. Place the bowl in ice water; let stand 5 minutes, stirring occasionally. Press plastic wrap onto surface. Chill 4 hours or until cold.
To assemble: Spread filling in the tart shell. Sprinkle with berries and citrus curls (or arrange berries in stripes). Serve immediately or chill, covered, up to 24 hours.