Potato, Onion, and Cheese Pasties

double batch of pie crust dough
2 1/2 cups diced potatoes
1 1/2 cup diced onion
1/4 cup half-and-half, or milk
1/2 cup ground mustard seed
1 1/2 cup grated or cubed cheese
1/2 tsp salt
1/2 tsp pepper
beaten egg and milk to glaze the crusts

Bring water to boil in a large pot over high heat. Add the potato and onion. Cover the pan and boil until the potatoes are soft (this timing depends on how small the pieces are). Remove from heat, strain away the water, and put the potatoes and onions in a large bowl.

Add the half-and-half to the bowl. Mash everything until the potatoes are smooth. Stir in the mustard, salt, pepper, and cheese.

Preheat oven to 400 F.

Make small balls of pastry dough and roll them out to small circles, about 5"-6" wide. Put a spoonful of filling onto each circle, wet the edges of the crust with water, then fold them in half, pinching the edges together. You should be able to make 8 pasties.

Place them on a baking sheet lined with parchment paper. Glaze the top with a mixture of beaten egg and a bit of milk. (I forgot this step, so my pasties were pale.) Bake for 20-25 minutes, until the crusts are golden brown.