Peel and finely chop the garlic, then gently fry in a thick-bottomed pan with 2 tablespoons of olive oil. Crumble in the chilli, add the oregano and tomatoes.
Mix gently, but do not break up the tomatoes as this will release the pips, which will make the sauce slightly bitter – by leaving the tomatoes whole and letting the mixture cook slowly you’ll get a nice sweet sauce. (You can remove the pips from the tomatoes if you want, but I don’t bother.) Bring to the boil and simmer gently for 1 hour.
Add the vinegar to the pan, then stir and chop up the tomatoes in the sauce.
Pick the basil or marjoram and roughly chop, then add to the pan.
Season well to taste with sea salt and black pepper, and finish with 2-3 tablespoons of extra virgin olive oil.