Soak the bread in the milk for a few minutes, and remove excess milk by squeezing the bread with your hands. Break up the bread into small pieces and add to a mixing bowl with the ground pork, ground beef, raisins, pine nuts, parsley, basil, Parmigiano cheese, and salt and pepper.
Add the eggs, and mix until the ingredients are evenly distributed. With your hands, shape the meatballs into the size of golf balls.
In a large pot, heat the extra-virgin olive oil and cook the onion until translucent. Add the wine, and tomato puree, and bring it to a boil. Add the uncooked meatballs to the pot and let cook on medium heat until cooked through, about 30 minutes.