Add the bell pepper, crushed tomatoes, tomato sauce, ketchup, and brown sugar into a blender or food processor. Blend until smooth.
Heat the oil in a pan over medium-high heat. Add in the onion and garlic. Sauté until the onion turns translucent.
Then add the ground beef into the pan. Cook and crumble the beef until it has browned and fully cooked. Mix in the salt, pepper, and Italian seasoning.
Pour the blended sauce into the pan and mix it together with the beef. When the mixture starts to bubble, reduce the heat and simmer for 3-4 minutes.
Remove the pan from heat and let it cool for 10 minutes. Serve the meat mixture with buns and enjoy!