Heat the oil in a heavy based saucepan or dutch oven, add the onions (for the sauce), celery and garlic and cook at a low temperature, stirring occasionally, for about 10 mins.
Add the oregano, crushed chilli flakes, passata and water and bring to the boil before turning the heat down to simmer gently (while you make the meatballs. ) Season to taste.
Put all the meatball ingredients into a large mixing bowl and mix together, gently, with your hands. Try not to over mix. *SEE NOTE 4
Roll the mixture into balls approx. 1tbsp inch in size. We made 28 from this mixture.
Nutritional information is a rough GUIDE only, calculated using an online nutrition calculator.