Heat brown gravy packet & water in a small saucepan. Add steak seasoning & heat until it comes to a boil. Set aside.
Roll out pie crust & fit it into a 9" or 10" pie dish. Trim excess crust. Fill the center of the pie crust with the leftover beef, potatoes, & carrots.
Pour the gravy on top. Roll out the second pie crust & lay it over the top. Trim excess crust. Pinch & crimp edges. And cut a couple slits into the top for ventilation.
Bake at 350˚F for a minimum of 1 hour. Use a thermometer to check if the filling has reached 165˚F. If the crust is getting too done, cover it with foil as it finishes baking.
Notes
It's IMPORTANT that the mixture is re-heated to 165˚F. And everything needs to be consumed in one sitting, since this is a leftovers dish. Having been ServSafe Certified, I know the importance of reheating food ONLY ONCE. If you can't eat the whole pie, bring dinner to your neighbors while it's hot.
If you have extra pie crust, cut out fun shapes like leaves to decorate the top. Just rub the bottom of the shape with water so it adheres to the top of the pie crust. Make sure you still have slits for ventilation as well.