Pre-heat the oven to 200°C, 400°F, Gas Mark 6.
Prepare meatballs by mixing the ingredients together. Shape into 24 small balls. Place on a baking sheet and bake for 20 minutes.
To prepare the sauce, soften the onion in the oil, add all the remaining ingredients and bring to the boil, stirring. Add the meatballs and simmer for 5 minutes.