Preheat the oven to 180°C.
Cut the beetroot, onions & tomatoes in half, arrange them in a large baking tray.
Cut the courgette, aubergine and bell pepper into chunks and tuck these between the tomatoes. Add the unpeeled garlic cloves.
Scatter the herbs and chilli flakes (if used) on top of the vegetables, then drizzle the oil and balsamic vinegar on top. Season to taste, then toss well.
Bake in the oven for 30 minutes or so.
When the veggies are tender, remove the tin from the oven and let it cool for a bit. Remove & discard the skin of the garlic, onion and beetroot (and peppers, if you prefer). Put all veggies in a liquidiser, including the cooking jus, add the basil leaves and process until you get a thick sauce.
You can refrigerate or freeze this sauce until needed.
Cook the meatballs according to the packet’s instructions. Mine had to be baked for 20 minutes - but some need to be pan-fried or grilled.
Pour the sauce into a saucepan, add the stock and bring to a simmer. (At this point you could add some spinach or green peas or shredded kale if you like). Simmer for a couple of minutes and serve with the meatballs.