Heat the oven to 200°C. Heat the oil over a medium heat and add the aubergine. Cook for 5 minutes then add the onion and garlic and cook for another 5-10 minutes until everything is softened.
Place the mixture in a food processor and pulse until mostly blended then tip out into a large bowl. Add the breadcrumbs, parmesan, basil, parsley, oregano and a sprinkle of salt and pepper then mix together until everything is combined. Add the egg and mix together again. Shape into small balls, I got about 20 out of the mixture and place on a greaseproof paper lined baking sheet. Place in the oven and cook for 20 minutes.
While the meatballs are cooking make the tomato sauce. Heat a drizzle of olive oil in a saucepan and add the onions. Cook for a couple of minutes then add the garlic and cook for another few minutes. Pour in the chopped tomatoes, Worcestershire sauce and oregano and cook on a medium heat for 10 minutes. Stir in the tomato puree and season to taste then remove from the heat.
Once the meatballs are finished cooking place them in a heatproof dish and top with the sauce. Tear the mozzarella over the top and place in the oven for 10 minutes then serve in brioche buns with a drizzle of truffle oil if desired.
Nutrition information does not include the sandwich buns.