Heat the oil in a large Dutch oven over medium-high heat. Season the beef with black pepper and cook for 5–8 minutes, until browned.
Add the onion, celery, and carrots and cook for 5 minutes. Stir in the garlic, tomato paste, and flour until the vegetables and beef are well coated.
Pour in the beef broth, gravy mix, Worcestershire sauce, soy sauce, and sugar. Stir well, then cover with a lid or foil.
Bake for 1 hour 20–30 minutes, or until the beef is fork-tender. Let the mixture rest for 5–10 minutes, then stir in the peas.
Increase the oven temperature to 400°F.
Transfer the beef mixture to a 9-inch pie plate. Brush the rim with beaten egg, then place the pie crust over the filling. Tuck the edges under, cut a small vent in the center with a few slits around it, and brush the top with the remaining egg. Sprinkle with black pepper and parsley.
Bake for 20–30 minutes, until the crust is golden brown. Let the pie cool for 15 minutes before serving.
Notes
Let the pie rest for 15 minutes before serving so the filling can set.
Fresh parsley is optional but adds a nice finishing touch.
Store leftovers in the refrigerator for up to 3 days and reheat before serving.