Heat a saute pan to medium heat. Add the oil and saute the onions, garlic and oregano until the onions are slightly caramelized. Set aside to cool.
In large bowl, mix the chilled tomato sauce with the bread. Add the ground beef, sausage, Parmesan, parsley, provolone, tomato paste, ham, mortadella, salami, raw eggs, hard-boiled eggs and the onion mixture and mix well.
Form 3-ounce meatballs and place them on a nonstick baking sheet, or a baking sheet lined with parchment paper or a baking mat. Bake until the meatballs are cooked through, 18 to 20 minutes.
For a larger yield, reduce the weight of each meatball.