Set a large, heavy skillet over medium-high heat. Add a drizzle of oil and cook the onion and pepper for 4-5 minutes, until soft. Add the ground beef and cook, breaking it up with a spoon, until it’s well crumbled and no longer pink. Add the taco seasoning, tomato sauce, ketchup, vinegar and Worcestershire sauce. Season with salt and pepper and cook, stirring occasionally, until saucy and thickened.