Finely chop the red onion and add the olive oil to a saucepan to heat up.

With the oil hot, sauté the onions until soft

Whilst the onions are cooking, grind up the fennel seeds in a pestle and mortar.

Add the ground fennel to the onions and let it cook for a minute.

Add the red wine vinegar to the saucepan and let the moisture simmer away.

Add the passata and nutmeg to the saucepan and bring to the boil.

Use a stick blender to liquidate until smooth (optional)

Salt to taste and simmer for 20 minutes.

Add the meatballs and simmer until heated through.

Serve over freshly cooked al dente spaghetti and sprinkle with shavings of some top notch Parmesan.