To make the meatballs, peel and chop the onions and garlic finely, or grate them if you want a finer texture.
In a bowl add the ground pork, chopped onion and garlic, mixed herbs, seasoning and mix well to combine.
Cut the mozzarella into small cubes.
Take about a tablespoon of the pork mixture, shape it into a ball, then flatten it out.
Add a cube of mozzarella in the middle, then bring the meat around it to fully enclose it, shaping it into a ball again.
Repeat with the remaining mixture.
In a pan, heat up one tablespoon of oil, add the meatballs to the pan, and gently fry until lightly brown, the meatballs will not be fully cooked at this stage.
Once they are brown, remove from the pan and set aside.
To make the sauce, peel and chop the onion and garlic, and fry them in the same pan the meatballs had been fried, add more oil if necessary.
Add the chopped tomatoes, broth, parmesan, seasoning and herbs, and transfer the meatballs back to the pan.
Cover the pan with a lid, and leave to cook until the sauce is reduced and the meatballs are cooked through.