Add ground beef and cook 3 to 5 minutes, breaking it up, until browned with no pink remaining. Drain excess fat.
Stir in ketchup, Worcestershire sauce, and taco seasoning. Cook 1 minute.
Pour in the cornstarch slurry, stir well, reduce heat to medium-low, and simmer 6 to 7 minutes until thickened.
Set oven to broil. Open buns and place them cut-side-up on a sheet pan.
Scoop meat mixture onto bottom buns and top each with provolone.
Broil 2 to 4 minutes, watching closely, until cheese melts and buns are toasted.
Add bun tops and serve warm.
Notes
Whisk the cornstarch into cold broth before adding it to the skillet so it does not clump. Cook peppers and onions separately if you need a picky-eater version. Watch the broiler closely because buns can burn quickly. Store meat without buns for up to 4 days, or freeze the meat mixture for up to 3 months.