In a food processor, combine the flour and salt. Add the butter and pulse a few times, until it forms pea-sized pieces. Add the yogurt and water. Pulse just until the dough starts coming together. Add more water as needed. Remove the dough from the food processor.
Using your hands, form the dough into 2 discs for the apple-raspberry slab pie or 6 discs for the meat and confit duck pies. In either case, refrigerate the discs of pastry for 1 hour before rolling out.