Start by preheating the oven to 350 degrees F.
Take a large mixing bowl and throw in the ground beef, onion, chopped bell pepper, garlic, egg, Worcestershire sauce, and the salt and black pepper.
Mix all these together until they’re thoroughly combined before moving on, as you need as even of a distribution as possible between the ingredients.
Take another smaller mixing bowl, and add to it the ketchup, mustard, brown sugar, and vinegar. Mix these together to create a smooth mixture.
Take a 9x13 baking dish, and spread half of the ketchup mixture over the bottom.
Over the top of this, press all of the beef mixture over it, patting it down gently so it fills up the entirety of the baking dish.
Take the second half of the ketchup mixture, and spread it over the top of the meatloaf to finish it off.
It's now ready to bake. Once the oven is up to temperature, just place it in the oven on the middle rack and let it bake for one hour.
And that’s it! Your simple but highly delicious meatloaf recipe is done!