Begin by combining ground beef, ground veal, and ground pork in a large bowl. Add the black pepper, kosher salt, crushed red pepper flakes, and warm nutmeg. Gently mix in the beaten egg, Parmesan, parsley, fresh bread crumbs, and dry breadcrumbs until everything is evenly distributed.
Tip: To avoid tough meatballs, mix gently. Overworking the meat will make them chewy.
Using your hands, form the mixture into ball-shaped portions. Aim for about two inches in diameter. You should yield around 20 meatballs, depending on how generous you are.
In a large skillet, heat a mix of vegetable oil and olive oil over medium heat. Carefully add the meatballs to the hot skillet, making sure not to overcrowd the pan. Brown them nicely on all sides, which takes about 5-6 minutes.
While the meatballs are cooking, heat the olive oil over medium heat in another large pot. Add the chopped onions and sauté until soft and translucent, about 5 minutes. Next, toss in the minced garlic and cook for an additional minute.
Tip: Caramelizing the onions adds a sweetness to the sauce that contrasts beautifully with the acidity of the tomatoes.
Carefully transfer the seared meatballs into the pot with the cooked onions and garlic. Pour in the crushed tomatoes, red wine, kosher salt, and oregano. Stir gently to combine, ensuring the meatballs are submerged in the sauce. Simmer on low heat for about 30 minutes.
While the sauce is simmering, cook your spaghetti according to the package instructions. Make sure to salt your water! When ready, drain the pasta but reserve a bit of the pasta water—this comes in handy later.
Toss the spaghetti with a splash of reserved pasta water for a silky texture, then place a generous portion of meatballs a