Directions

1. To make the dough, mix the flours with the salt together in a large mixing bowl. Using your fingers, rub the cold cubed butter into the flour until the largest pieces of butter are the size peas. Whisk the yoghurt and ice water together, and then incorporate into flour mixture, using a wooden spoon or spatula. Mix the dough and continue adding more ice water, a little at a time, just until the dough comes together into a ball. I usually end up adding an additional 1/4 cup of ice water, but it depends on the type of flour you use. The dough should be just moist enough to come together into a ball, but not so wet that it is sticky when you handle it. Do not over-mix the dough. Shape the dough into two balls, flatten into discs, and refrigerate for 30 to 60 minutes.
2. (Optional: If you've got some time on your hands and want to take your pie crust to the next level of fabulous flakiness, you can do two additional steps called fraisage and roll-fold-roll. These are explained in full detail at Bojon Gourmet. They will turn your dough almost into a puff pastry. But if you don't have time for them, don't worry, your pie crust will still be perfectly flaky as is.)
3. While your dough is chilling in the fridge, make the filling by grating the zucchinis on the medium-sized holes of a box grater. After you have about 3 to 4 cups, place in a bowl, and mix in the salt. Allow to sit for about 10 minutes, giving time for the salt to draw out the liquid. Now take small batches of grated zucchini at a time, and using both hands, squeeze out as much liquid as you can. Discard the liquid and measure the zucchini again, after the water's been squeezed out. You should end up with 2 cups (don't pack it down).
4. Place the zucchini and all the remaining filling ingredients into a medium bowl and mix together well.
5. After 30 to 60 minutes in the fridge, remove the dough discs and sprinkle some flour on your countertop and rolling pin. Roll each disc into a large rectangle, about 1/8 inch thick. Cut this large rectangle into about 6 (maybe 8) smaller rectangles measuring very roughly 4 (or 5) x 6 inches each. Place about 1 1/2 Tbsp of filling on one half of each rectangle. Brush a little water around the edges of the rectangle, and fold the rectangle in half, covering the filling. Press the edges together well to seal. Using a spatula, transfer the pies to a baking sheet and refrigerate for 15 minutes. After refrigeration, use the tines of a fork to further press the edges together, creating a nice decorated edge. Slice two vent holes into the top of each pie. Brush the tops with egg wash. Bake for about 30 minutes, or until golden, at 375 F.