Heat the oil in a 4-quart saucepan
or large Dutch oven
over medium heat. Add the onions
and cook until translucent, 2 minutes. Add the salt and garlic and cook until everything is soft but not browned, about 3 minutes.
Squeeze the tomatoes
one by one into the pan, pulverizing them by hand, and pour in their juice, too. Add the bones, wine
, oregano, red pepper flakes, if using, black pepper and bay leaf. Bring the sauce to a simmer, and then reduce the heat to its lowest possible setting, and continue to cook for 8 hours. The sauce should reduce by about one-third.
Taste for seasoning and add more salt if necessary. Remove the bones and bay leaf. If not using right away, let the sauce cool, then cover and refrigerate for up to 1 week or freeze for up to 2 months.