Double-Crust Mixed Berry Pies

Steps

1. Make the pastry first: whisk the flour, the salt and 30 g of the sugar in a large bowl.
2. Cut the butter into the flour mixture with a pastry cutter or your fingertips until most pieces are pea-sized, with some larger flakes.
3. Drizzle in the water a little at a time, tossing with a fork, until the dough holds together when squeezed.
4. Divide the dough into 4 equal pieces (2 bottoms, 2 lids), flatten each into a disk, wrap and chill for at least 1 hour.
5. While the dough chills, make the filling: in a large bowl, gently toss the blueberries, strawberries and raspberries with the remaining sugar, the cornstarch, the lemon juice, the lemon zest and the cinnamon. Let it stand 15 minutes.
6. Place a rack in the lower third of the oven, set a baking sheet on it and preheat to 400°F (200°C).
7. Roll 2 of the dough disks into 12-inch rounds and fit them into two 9-inch pie plates.
8. Divide the berry filling evenly between the two crusts, half in each, including any juices.
9. Roll the remaining 2 dough disks into 11-inch rounds and lay one over each pie. Trim, fold the edges under, crimp to seal, and cut several vents in each lid.
10. Whisk the egg with the milk and brush it over both lids. Chill the pies 15 minutes so the pastry stays flaky.
11. Bake on the hot baking sheet for 20 minutes, then lower the oven to 375°F (190°C) and bake 40 to 50 minutes more, until the crust is deep golden and the filling bubbles thickly through the vents. Tent the edges with foil if they brown too fast.
12. Cool the pies on a rack for at least 3 hours so the filling sets, then cut each into 6 slices.