Heat the bacon grease in a large skillet until hot.
Then add in the garlic and sauté for 2-3 minutes.
Add the onion, mushrooms, and bell pepper in with the garlic and sauté for another 3-5 minutes.
Add the ground beef into the skillet, stirring the garlic, onion, mushrooms, and bell pepper into the meat. Cook on medium heat for 15 to 20 minutes, or until the meat is well cooked.
Be sure to drain off any excess oil when the meat has finished cooking
Whisk together the beef broth and flour in a separate measuring cup.
Mix the beef broth mixture, Worcestershire sauce, dry mustard, salt, and black pepper into the meat, stirring until combined.
Let the cheesesteak sloppy joe mixture simmer for a good 5-10 minutes.
Finally, top the meat with the Provolone right in the skillet and let it melt.** Then stir the melted cheese into the meat mixture.
Serve on toasted buns or on a bed of lettuce or spinach.