Sauté the onion and green bell pepper in a large skillet over medium heat for about 5 minutes until softened.

Add the ground beef to the skillet and cook until browned, stirring occasionally (about 7 minutes). Drain excess fat if necessary.

Mix in ketchup, Worcestershire sauce, garlic powder, brown sugar, salt, and pepper. Stir until combined.

Reduce heat to low and let the mixture simmer for about 10 minutes to meld flavors.

Toast hamburger buns in another skillet or under a broiler until golden brown.

Serve the meat mixture generously on each bun and add optional garnishes like pickles or coleslaw.