To a large frying pan or skillet, over medium-high heat, add the extra virgin olive oil and heat, then add the garlic cloves and fry for a minute or so until fragrant, then add the chilli flakes, stirring well with a wooden spoon or spatula to combine.
When the garlic cloves start to brown and sizzle and splutter, remove the cloves and set them aside but do not discard.
Immediately add the finely diced onions to the pan and fry, stirring only occasionally so the onions don’t burn and adjusting the heat as necessary, until they’re soft, almost translucent and aromatic.
Add the crushed tomatoes, tomato paste, and sea salt, and stir to combine well. If you’re a garlic lover, return the garlic cloves to the sauce now; if you’re not, leave them out.
Turn the heat to high so the sauce is bubbling. It will reduce fairly quickly on high heat, so stir the sauce occasionally.
When the tomato sauce is thick and luscious, turn the heat to low, taste, and adjust the seasoning, adding more salt if needed; if it’s a little acidic, add some sugar. If you’re a fan of basil, add the leaves now and stir to combine.
If serving with pasta or meatballs – add the cooked pasta and/or meatballs to the pan and simmer a little before plating. Otherwise, remove from the heat, leave to cool, then transfer to a jar and refrigerate for later use. It’s fantastic spread onto pizza or parmas.