Put the garlic and onions in a food processor along with a small splash of olive oil. Pulse until it turns into a lightly chunky paste, then transfer to a large mixing bowl.

Add the meat to the bowl along with the oregano, balsamic, a large pinch is salt and several grinds of black pepper. Add 2/3 of the panko and knead until uniform. If it still seems a little loose, add the remaining panko. Form the meat into balls a little larger than golf balls; you should end up with around 15. Transfer them to a tray and let rest for 15 minutes, before popping them into a 400 F preheated oven for 20 to 25 minutes.

Add a splash of olive oil to a large pan on medium heat. Add the onions and let fry until the onions are well browned, about 10 minutes. Add the garlic, pepper flakes and tomato paste and let cook until the tomato paste dries out a bit, about 5 minutes. Add the tomatoes, crushing them in your hands as you drop them in. Pour in the tomato liquid as well. Bring to a simmer and let reduce for about 10 minutes.

Check the sauce for seasoning and add salt and pepper as needed. Transfer the meatballs to the sauce and toss to coat. Let cook a final 5 minutes so everything can meld. Sprinkle in the basil, then serve with freshly grated parmesan.