In a large mixing bowl, whisk together the all-purpose flour and salt. Add chilled butter, cutting it in until it resembles coarse crumbs. Gradually add cold water until the dough holds together. Refrigerate for at least 30 minutes.

In a large skillet over medium heat, sauté chopped onions until translucent. Increase heat and add cubed beef, browning it for 10 minutes. Stir in diced rutabaga and potatoes, seasoning with Worcestershire sauce, herbs, salt, and pepper. Cook until vegetables are tender, then cool.

Flour a clean surface and roll out the chilled pastry dough to about 1/8-inch thickness. Cut out circles. Place a generous scoop of the beef filling in the center of each circle. Fold the dough over and crimp edges to seal tightly.

Preheat your oven to 350°F (175°C). Brush the tops of filled pasties with beaten egg. Bake for 30-35 minutes or until golden brown.

Cool on a wire rack for 5 minutes before serving. Enjoy warm with your favorite gravy or slaw.