Preheat oven to 350 degrees F. and line a large rimming baking sheet with parchment paper. Set aside.
Add the ground beef, diced onion, bread crumbs, milk, eggs, ketchup, Worcestershire sauce, Dijon mustard, parsley, oregano, garlic powder, thyme, salt, and pepper to a large mixing bowl. Use your hands to thoroughly mix and mash the ingredients together until completely combined.
Whisk together the glaze. Add the ketchup, Dijon mustard, brown sugar, and red wine vinegar to a small mixing bowl. Whisk well to combine. Set aside.
Transfer your meat mixture to the prepared baking sheet lined with parchment paper. Use your hands to shape the meat into a large loaf-shape (you may also add your meat mixture to two greased loaf pans if preferred).
Use a pastry brush to brush the surface of your loaf with half of your pre-made glaze. Reserve remaining glaze.
Bake, tented with foil, for 45 minutes. After 45 minutes, increase the oven temperature to 400 F and remove the foil. Brush the surface with the remaining glaze and continue to bake for 15-20 minutes, or until internal temperature registers 160 degrees F.
Remove from the oven and allow to rest for 5 minutes before slicing and serving. Enjoy!