Preheat the oven to 350°F and then line a baking sheet with aluminum foil.
Add the lean ground beef, finely chopped onion, bread crumbs, milk, eggs, garlic powder, onion powder, salt, pepper and tomato paste to a large bowl. Mix it together really well.
Create a loaf shape by forming with your hands or by packing the beef mixture into a greased loaf pan and then flipping it over onto the baking sheet. Remove the loaf pan and it will create the perfect loaf shape.
Bake the meatloaf uncovered and without the sauce topping for 40 minutes. While the meatloaf is cooking, mix together the ketchup and white vinegar. Remove the meatloaf from the oven and spread the ketchup mixture along the top and sides. Bake uncovered for another 10 minutes or until fully cooked inside.
Once cooked, Let the meatloaf sit for 10 minutes to allow the juices inside the meatloaf to distribute evenly. Slice into pieces and serve.