Heat a large saucepan over a medium heat and add the olive oil. Once hot, add the onion and cook gently without browning for 4–5 minutes, or until softened and translucent. Add the garlic, continue to cook for 2 minutes until aromatic, then add the dried herbs, tomatoes and stock. Bring the sauce to a simmer, reduce the heat and simmer gently while you make the meatballs.