In a large skillet, cook ground beef and onion for 5 minutes. Stir in potatoes and fresh veggies, if using. Stir in seasonings. Cook until potatoes are fork tender, about 15-20 minutes. (If using frozen veggies, stir into skillet shortly before removing from heat.) Cool.
Roll out dough into a circle, about the size of a small plate. (If using store bought dough, cut each piece of dough into fourths and roll into a circle.) Place about 1/3 c. beef filling into the center of each dough circle. Fold over, seal and roll edges.
Brush each pasty with beaten egg yolk and bake at 350 degrees for 25-30 minutes, until golden and pie crust is fully cooked.
While pasties cook, melt butter or margarine in a small saucepan. Whisk in flour and cook 2 minutes. Whisk in beef stock, bring to a slow boil and boil until thickened. Stir in Worcestershire sauce and Italian seasoning.
Serve pasties with gravy on the side for dipping or poured on top.