Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the lean ground beef, grated onion, minced garlic, ketchup, milk, eggs, chopped parsley, panko breadcrumbs, salt, pepper, and Italian seasoning. Mix until just combined.
Transfer the mixture into a loaf pan, shaping it into a loaf form.
In a small bowl, combine the ketchup, white vinegar, and brown sugar. Spread the glaze over the top of the meatloaf.
Place the loaf pan in the preheated oven and bake for about 50-60 minutes or until the internal temperature reaches 160°F (70°C).
Once cooked, let the meatloaf rest for about 10 minutes before slicing.
Carefully slice the meatloaf and serve it warm.