Mix together flour and salt in a large bowl, then cut in butter with a pastry cutter until it is crumbled into small bits resembling breadcrumbs.
Add cold water while mixing until the dough forms into a ball. Briefly knead the dough then set in the refrigerator for one hour.
Assembly
Prepare the filling by mixing the vegetables, herbs and seasonings in a bowl and crumbling the hamburger in a separate dish.
Remove dough from the fridge and cut into six equal pieces then roll flat into rounds ⅛" thick.
Build the pasties by adding equal amounts of the vegetable mixture to each one then top with crumbled ground beef and 1 teaspoon of butter.
Fold dough shut over the filling ingredients and crimp with a fork to seal.
Paint the exterior of the dough with beaten egg then sprinkle lightly with salt.
Baking
Preheat oven to 350 degrees.
Set on a prepared baking sheet and bake in the oven for 1 hour, or until the interior is hot and the crust is golden brown.
Notes
If using a fatty ground beef such as 80/20, the butter can be omitted as there will be enough fat to provide moisture. However, I like using a leaner ground beef and adding butter for the fat because it has better flavor.