Heat olive oil in a large skillet over medium high heat. Add in the bell pepper and onion. Cook for 2-3 minutes until softened.
Add in the ground beef. Continue cooking over medium heat. Breaking up the meat while it cooks. Cook until the meat is completely browned, approximately 5 minutes.
Once the meat is browned and the onion and peppers are tender, add in the garlic. Cook an additional 30 seconds.
Add in the tomato paste, Worcestershire sauce, tomato sauce, ground mustard, molasses, apple cider vinegar, chili powder, paprika, salt and pepper. Stir to coat the meat.
Bring to a low simmer, allow the meat to cook in the sauce, uncovered, for 5-10 minutes until the sauce reduces and mixture is thick.
During this time prepare the hamburger buns by spreading a little butter on the insides and toasting in a skillet.
Serve the sloppy joes warm.