Add the ground-beef into a large cast iron skillet (this brwn well) and brown before a deep brownish crust looks prior to breaking up the beef aside.
Stir the ground beef & brown till a profound crust seems about 50% of the beef.
Remove the beef (you may leave the fat) & add the egg and the onions and bell-peppers and mushrooms.
Let brownish for 1-2minutes before stirring, then let brown for another 1-2minutes before stirring.
Add the beef back in-the pan.
In a small cup mix the beef broth and cornstarch together.
Add the ketchup, Worcestershire-sauce, salt, black-pepper, steak broth/cornstarch mix into the pan.
Cook until the mix is simply slightly liquidy (roughly 75% of the mix is over liquid), 3-5minutes.
Switch off the heat, add the provolone-cheese.
Served on toasted brioche buns.