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.
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 and crimp with a fork to seal.
Paint the exterior of the dough with beaten egg then sprinkle lightly with salt.
Preheat oven to 350 degrees.
Set on baking sheet and bake in oven for 1 hour.
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.