Heat the olive oil in a skillet pan, over medium-high heat, and add the diced onion and diced green pepper. Cook for 3-4 minutes, stirring frequently, until the veggies are softened.
1 tablespoon extra-virgin olive oil, 1/2 cup finely diced yellow onion, 1/2 cup finely diced green bell pepper
Add the ground beef into the skillet pan. Cook and crumble until the beef is no longer pink. Drain any excess grease from the pan.
1 pound lean ground beef
Stir in the tomato sauce, Worcestershire sauce, brown sugar, garlic powder, ground mustard, kosher salt, and black pepper.
1 can (15 oz) tomato sauce, 2 tablespoons Worcestershire sauce, 2 tablespoons light brown sugar, ½ teaspoon garlic powder, ½ teaspoon ground mustard, ¼ teaspoon kosher salt, ¼ teaspoon black pepper
Bring to a gentle boil. Once boiling, reduce the heat to LOW and let it simmer for 15 minutes, stirring it occasionally, until thickened and flavors combined (very fragrant).
Serve inside hamburger buns. Enjoy!