Pass the tomatoes and their liquid through a food mill fitted with the fine disc. Set aside.

Heat the olive oil in a heavy 4- to 5-quart pot over medium heat. Add the onions and cook, stirring occasionally, until golden, about 8 minutes. Make a little room in the center of the pot, dump in the garlic, and cook, stirring, until the garlic is lightly browned, about 2 minutes. Add the pork bones and cook, turning, until lightly browned on all sides, about 5 minutes. Add the ground beef and pork and season lightly with salt. Cook, stirring to break up the meat, until the meat changes color and the water it gives off is boiled away, about 10 minutes. Continue cooking until the meat is browned, about 5 minutes. Add the bay leaves and oregano, then pour in the wine. Bring to a boil and cook, scraping up the brown bits that cling to the pot, until the wine is almost completely evaporated. Pour in the tomatoes, then stir in the tomato paste until it is dissolved. Season lightly with salt. Bring to a boil, adjust the heat to a lively simmer, and cook, uncovered, stirring often, until the sauce takes on a deep, brick-red color, 2 to 3 hours. Add the hot water, about 1/2 cup at a time, as necessary to maintain the level of liquid for the length of time the sauce cooks.

Skim off any fat floating on top and adjust the seasoning as necessary. The sauce can be prepared entirely in advance and refrigerated for up to 5 days, or frozen for up to 3 months