1) Put the minced beef in a bowl. 2) Peel and crush the garlic and add it to the beef with the breadcrumbs, herbs, salt, pepper and the beaten egg. 3) Mix well to bind, then with lightly floured hands, form the mixture into 8 small balls. 4) Heat the oil in a frying pan and fry them for about 5 minutes until browned on all sides. Remove and drain on kitchen paper. 5) Peel and finely chop the onion and fry it in the oil in the pan until it turns golden. 6) Rinse and slice the mushrooms and add them to the pan with the tomatoes and their juices and the basil. 7) Break down the tomatoes and season the mixture with salt and pepper. Pour in the stock. 8) Bring to the boil, add the meatballs and simmer for 30 minutes.