In a large skillet, add olive oil, ground beef, diced onion, and green peppers. Cook over medium-high heat until the beef is browned and vegetables are softened, about 5 to 8 minutes. Crumble beef as it cooks and stir frequently.
Drain the mixture very well to remove excess grease and liquid.
Add tomato sauce, tomato paste, ketchup, brown sugar, Worcestershire sauce, garlic powder, salt, and pepper. Mix well and bring to a simmer.
Reduce heat to medium-low and let simmer for 5 to 8 minutes, until thickened as desired. The mixture will thicken further as it cools.
Serve hot on hamburger buns. Leftovers can be stored in an airtight container in the refrigerator for up to 5 days or frozen for up to 3 months.
Notes
For extra flavor, consider adding diced green onions or a dash of hot sauce.