Mix together beef and pork using your hands. Stir in garlic, cheese, parsley, eggs, and 1 1/4 teaspoons salt; season with pepper. Soak bread in milk for 5 minutes, and then stir into meat mixture. Lightly dampen hands, and roll mixture into 1 1/2-inch balls, transferring to a rimmed baking sheet as you work. Refrigerate for 1 hour.

Bring sauce to a gentle simmer in a medium pot. Meanwhile, heat oil in a heavy medium skillet over medium-high heat. Working in batches, fry meatballs, shaking skillet occasionally, until brown all over, about 6 minutes, and transfer to sauce. Simmer until meatballs are cooked through, about 10 minutes. (Test doneness by cutting 1 meatball open.)