Finely chop the onion and green bell pepper. Mince the garlic. Gather all other sauce ingredients.

Heat the olive oil in a large skillet or Dutch oven over medium-high heat. Add the ground beef and cook, breaking it apart with a wooden spoon, until browned and no longer pink, about 6-8 minutes.

Drain off any excess grease from the skillet.

Reduce heat to medium. Add the chopped onion and green bell pepper to the skillet with the beef. Cook, stirring occasionally, until softened, about 5-7 minutes.

Add the minced garlic and cook for another minute until fragrant.

Stir in the ketchup, tomato paste, Worcestershire sauce, yellow mustard, light brown sugar, chili powder, salt, and black pepper.

Pour in the water or beef broth. Bring the mixture to a simmer, then reduce the heat to low, cover, and let it cook for at least 15 minutes, stirring occasionally, to allow the flavors to meld and the sauce to thicken slightly. For a thicker sauce, simmer uncovered for the last 5-10 minutes.

While the sloppy joe mixture simmers, lightly toast the hamburger buns.

Spoon a generous amount of the hot sloppy joe mixture onto the bottom half of each toasted bun. Top with the other bun half.

Serve immediately with optional dill pickles and shredded cheese.