Heat the oil in a large skillet over medium heat. Add the onion and bell pepper and sauté, stirring often, until softened; about 5 minutes.
Crumble the ground beef into the pan and cook, stirring often, until completely browned. Drain off some of the excess fat if desired.
Add the ketchup, Worcestershire sauce, and taco seasoning; stir well.
In a small bowl, whisk together the cornstarch and chicken broth. Add the mixture to the cooked meat and stir well.
Allow the meat to simmer for 6-8 minutes, stirring often, until the sauce is thickened.
Line a baking sheet with foil and place the bottoms of the hamburger buns in a single layer on the cookie sheet. Scoop the sloppy joe mixture onto the buns, then top each with 1-2slices of provolone cheese.
Set the oven to broil, then broil the sandwiches until the cheese is melted, about 2-3 minutes.
Top the sloppy joes with the top buns.