Place steak cubes, flour, garlic salt, pepper, paprika and cumin into a large plastic storage bag. Seal bag and toss to coat.
In a large Dutch oven or heavy bottomed pot, heat the oil and butter. Add flour coated steak. Cook over medium-high heat just until browned on all sides.
To the steak add the beef broth, ketchup, steak sauce, mushrooms, onion, thyme and bay leaf, stir to combine. Bring to a boil then Immediately lower the heat to medium low, Replace the lid and simmer for 45 minutes.
Uncover and add the cubed potatoes to the pot. Cover and simmer for another 30 minutes or until the potatoes are fork tender.
Remove pot from the heat and remove the bay leaf and thyme. Cool slightly or chill overnight. (Tip: Filling may be chilled then placed into freezer bag and frozen for future meal).
Prepare: Preheat the oven to 350°F. Bring pie crusts to room temperature per package instructions. Fit one crust firmly onto the bottom and sides of a 10-inch cast iron skillet, brushed lightly with melted butter or vegetable oil.
Pour the beef mixture into the crust. Top with second crust crimping the edges together to seal. Cut slits on top using a sharp knife. Brush the top crust with beaten egg
Bake for 40-45 minutes until golden brown. Let stand for 10 minutes, then slice and serve.