For the meatballs:
1/2 pound ground veal
1/2 pound ground pork
1 pound ground beef
1 1/4 cups fresh white bread crumbs (about 5 slices, crusts removed)
2 tablespoons chopped fresh flat-leaf parsley
1/2 cup freshly grated Parmesan cheese
2 teaspoons kosher salt
1/2 teaspoon freshly ground black pepper, or more to taste
1 teaspoon onion powder
1 extra-large egg, beaten
Vegetable oil
Olive oil

For the sauce:
1 tablespoon good olive oil
1 cup chopped yellow onion (1 onion)
1 1/2 teaspoons minced garlic
Pinch of red pepper flakes
1/2 cup good red wine
1 (14-ounce) can pureed tomatoes
1 (14-ounce) can chopped or diced tomatoes
1 tablespoon chopped fresh flat-leaf parsley
1 1/2 teaspoons kosher salt
1/2 teaspoon freshly ground black pepper

For serving:
1 1/2 pounds spaghetti, cooked according to package directions
Freshly grated Parmesan