Place the ground meats, bread crumbs, parsley, Parmesan, salt, pepper, nutmeg, egg, and 3/4 cup warm water in a bowl. Combine very lightly with a fork. Using your hands or an ice cream scoop, lightly form the mixture into 2-inch meatballs.
Pour equal amounts of vegetable oil and olive oil into a large (12-inch) skillet or Dutch oven, to a depth of 1/4-inch. Heat the oil. Very carefully, in batches, place the meatballs in the oil and brown them well on all sides over medium-low heat, turning carefully. This should take about 10 minutes for each batch. Don't crowd the meatballs. Remove the meatballs to a plate covered with paper towels. Discard the oil but don't clean the pan.
For the sauce, pour the Rao's into the pan and stir.
Return the meatballs to the sauce, cover, and simmer on the lowest heat for 25 to 30 minutes, until the meatballs are cooked through. Stir in fresh parsley. Serve hot on cooked spaghetti and add the grated Parmesan as desired.