Place a large wide pan on the stove and pour in the tomato sauce.
Heat the pan and sauce on medium.
Use a small (or regular) food processor to tear apart the bread into very small pieces, like bread large crumbs.
Place the shredded bread and milk in a small bowl and mix, to coat the bread completely. Let sit for 5 minutes.
In a large bowl, place the ground meats, salt, ground pepper, onion, garlic, parsley, basil, olive oil and soaked bread pieces.
Toss all the ingredients with your (washed) hands to mix well.
Use a soup spoon or small cookie dough scoop to measure out potions of the meat mixture.
Roll the portions of meat between your hands to form meat "balls".
Place each meatball in the sauce while forming them. It might feel like a tight squeeze by the end, but don't worry, they'll shrink a bit while cooking.
Once all the meatball mix is used up and all the meatballs are in the sauce, raise the heat to medium high until the sauce starts to boil/bubble.
Lower the heat to medium and cover. Cook / simmer for 30 minutes.
Your meatballs are ready to serve with your favourite pasta, in a sandwich or on their own as an appetizer.