Blueberry & Greek Yogurt Breakfast Galette

Combine the dry ingredients by stirring the flour, sugar and salt in a large bowl. Add the oil. Using a pastry cutter, electric beaters or a mixer fitted with the paddle attachment, blend until the flour looks evenly crumbly.
Adding a little vegetable oil to the flour before adding the butter is another secret for tender and flaky pie dough. The oil coats the flour so that it won’t overhydrate when the water is added. Too much water develops the protein in the flour, which is why a crust becomes tough or shrinks when it bakes.
Add the butter and cut in until the dough is rough and crumbly, but small pieces of butter are still visible.
Working with cool—but not ice-cold—butter is easiest. Pull your butter from the fridge for about 30 minutes before making your dough, and it will cut into the flour quickly and more evenly.
Add the liquids. Place the water and vinegar (or lemon juice) in a small bowl, stir together and then add all at once to the flour mixture, mixing just until the dough comes together. Shape it into two discs, wrap well and chill until firm, at least 1 hour.
While butter is ideal, if you prefer to use vegetable shortening, omit the oil and increase the added water to 7 Tbsp (105 mL). This balances the fat-to-water ratio, since butter is 80% fat and shortening is 100% fat.
If you are not making the galette immediately, refrigerate the dough, well wrapped, for up to 2 days, or freeze it for up to 3 months. Thaw it overnight in the fridge before rolling.

Preheat the oven to 375°F (190°C). Pull the pie dough from the fridge 30 minutes before rolling. Line a baking tray with parchment paper. Dust a work surface with flour.
Roll out the dough on a lightly floured surface to a circle just less than 1⁄4 inch (6 mm) thick and about 16 inches (41 cm) across. Carefully lift the pastry onto the prepared baking tray and leave it untrimmed.  If making individual galettes, it’s OK if your rolled-out pastry pieces overlap on the baking tray. Just make sure you have space to add the yogurt and blueberry fillings to each one.
Fill the galette. Combine the Greek yogurt with the honey and lemon zest, then whisk in the egg. Dollop the yogurt in the centre of the dough and spread it out to about 6 inches (15 cm) across. Sprinkle the blueberries over the yogurt. Fold the edges of the pastry over the filling in five to six folds.
Make the egg wash by whisking together the egg and water. Brush the top of the pastry with egg wash.
Bake the galette for about 40 minutes, until the pastry is a rich golden brown.
Cool the galette on a rack for at least 30 minutes. Serve warm or at room  temperature, drizzled with honey.  The galette will keep, wrapped in plastic, in the fridge for up to 2 days.