Preheat oven to 200oC.
For the croutons, warm the oil in a frying pan and add then tear the bread into cubes and add this to the pan. Toss and cook until slightly golden. Add the sea salt & oregano. Toss to combine. Set aside.
Quarter the tomatoes and then use a small spoon to scoop out the watery flesh & seeds. Discard these.
Place the quartered tomatoes & garlic cloves (unpeeled) on a baking tray. Drizzle over 50 ml of the oil & scatter with sea salt. Bake for approx 40-45 minutes.
Cook the pasta until it is slightly less than al dente. Drain (reserve a ladleful of the cooking water).
Sauté the onion & basil stems in a frying pan with the remaining oil until it is aromatic and has softened. Add the vinegar & cook for a minute or two to lift up all the base flavours from the pan.
Add the tomatoes and stir.
Add a few of the fresh basil leaves to help flavour the sauce. These will likely blacken during cooking and you can discard them when serving if they do.
Squeeze the garlic from their skins and add these to the frying pan. Squash them down gently with your cooking spoon.
Taste the sauce and adjust the seasoning if necessary.
Add the pasta to the sauce and cook over medium-high heat until all the liquid is absorbed and the pasta is al dente. Use the reserved pasta cooking water if it needs loosening.
Taste again and adjust the salt if necessary.
Transfer to a platter. Add the croutons and remaining fresh basil leaves. Scatter with parmigiano-reggiano, to serve. You may also like to finish it with a drizzle of extra virgin olive oil & a little freshly squeezed lemon juice (optional).