Makes enough for 1 double crust
The pie dough recipe (see recipe) is great for fruit pies and chocolate pies. But a savory meat or seafood pie needs a heartier dough. Adding the mashed potato and egg yolk to the dough gives you a dough sturdy enough to stand up to elk or salmon.
Cook the potato. Set a small pot over high heat. Fill it three-quarters full with cold water and enough salt to make the water taste like the ocean, plus the chopped potato. Bring the water to a boil, then turn down the heat to low to simmer the water. Cook the potato until a knife runs through it easily, about 15 minutes. Push the soft potato through a ricer or fine-mesh sieve. Set it aside to cool.
Make the dough. Put the flour and salt into the bowl of a food processor and whirl them up. Add the cold butter chunks and pulse the food processor until the flour is sandy and the butter is the size of lima beans. Add the egg yolk and cooled potato and pulse until the dough is well combined. Dump the dough onto a clean, cool surface. Gently, move the dough around with your hands until it comes together into a ball. Form it into a disk. Wrap in plastic wrap and refrigerate for 30 minutes.