I wouldn't put this up against an Italian mother's gravy and meatballs, but it's pretty good, especially as a sub sandwich.
Preheat oven to 450 degrees.
In a medium bowl, beat eggs lightly; add milk and bread and let stand for about 5 minutes. Add ground beef, pork, onion, garlic, salt and paper; mix gently until well blended -- don't over mix or the meatballs will be too dense. Shape into about 24 meatballs, about 1-1/2 inches in diameter. Place in a parchment paper covered shallow baking pan and bake for 25 minutes.
Meanwhile, in a Dutch oven, heat oil over medium heat. Saute onion until tender and just begins to turn golden. Add remaining sauce ingredients; bring to a boil. Reduce heat, cover, and simmer for 30 minutes. Taste and adjust seasoning, adding more salt if necessary. Add meatballs; cover and simmer for 50 to 60 minutes longer, stirring occasionally.
Serve over spaghetti with Parmesan cheese. Alternatively, place meatballs and sauce on Italian bread, cover with mozzarella cheese, and put briefly under broiler until cheese melts/browns, keeping close watch to make sure the bread doesn't burn.