Peel the onion and 2 cloves of garlic. Coarsely grate them on a box grater with the courgette and mushrooms, then tip everything into a large frying pan on a medium heat with 1 tablespoon of olive oil. Cook for 10 minutes, or until softened.
Tip the cooked vegetables into a bowl and leave to cool. Add the minced beef and pork into the cooled vegetables along with the breadcrumbs. Finely grate in most of the Parmesan cheese and crack in the egg, then season with a little black pepper. With clean hands, squish and squash the mixture together until it’s all nicely combined. Now wash your hands!
With wet hands, take tablespoons of the mixture and shape into 24 little balls. Pop them onto a tray and leave in the fridge to firm up for 10 minutes or so. Wash your hands again.
Place a large non-stick frying pan on a medium heat with 1 teaspoon of oil. Add the balls into the pan and cook for 8 to 10 minutes, or until golden brown and gnarly all over, turning regularly.
Peel and finely chop the remaining garlic cloves. Create a little space in the pan in between the meatballs, add the garlic for 2 minutes, then pour in the passata. Give the pan a gentle shake so the balls are evenly coated in the sauce. Simmer for 30 minutes, or until the meatballs are cooked through and the sauce is thick and delicious, stirring occasionally.
