Brown the ground beef in a skillet over medium heat, breaking it into crumbles with a spatula.
Add the diced onion and bell pepper, cooking until softened, about 5 minutes.
Stir in minced garlic, cooking for another minute until fragrant.
Incorporate tomato sauce, tomato paste, brown sugar, Worcestershire sauce, and chili powder, stirring well to combine.
Reduce the heat to low and simmer for 15-20 minutes, stirring occasionally.
Season with salt and pepper to taste, adjusting the flavors as needed.
Serve the mixture on the hamburger buns, garnishing as desired.