Preheat your oven to 350°F (175°C) and line a baking sheet with foil.

In a large mixing bowl, combine the lean ground beef, diced onion, bread crumbs, milk, and eggs. Add garlic powder, onion powder, salt, pepper, and tomato paste. Mix gently until just combined to avoid overmixing.

Shape the mixture into a loaf or pack it into a greased loaf pan. Place it onto the prepared baking sheet.

Bake the meatloaf uncovered for about 40 minutes, until the top is browned.

Prepare the topping by mixing ketchup and white vinegar in a small bowl.

Spread the ketchup mixture over the meatloaf and bake for an additional 10 minutes.

Let the meatloaf rest for 10 minutes before slicing to lock in the juices.