Combine ground meat and rest for 30 mins.
In a large mixing bowl, combine the ground pork shoulder and ground beef chuck. Use your hands to mix thoroughly until the meats are well combined. Let this mixture rest for 30 minutes before adding seasonings.
Prep buttermilk mixture.
While the meat is resting, prep your buttermilk mixture that will be going into the meatballs. In a small bowl, combine buttermilk and gelatin. Stir to incorporate. Let this mixture sit for 10-15 minutes. Soak the slices of white bread in the buttermilk mixture until the bread becomes very, very soft, and almost disintegrates and becomes paste-like.
Combine meat and rest of meatball ingredients.
When the ground meat has rested for 30 minutes, eggs, anchovies, 1 tsp. soy sauce, grated parmesan, minced or grated garlic, chopped parsley, and buttermilk mixture, along with the soaked white bread. Use your hands to mix and combine everything until well incorporated.
One the meatball mixture is combined well, begin to form the meatballs. Wet your hands before doing so – this will prevent the meat mixture from sticking to your hands when you’re rolling the meatballs. Take about 2-3 tbsp. of mixture and rolling into a circular ball. Keep a baking tray or platter around lined with paper towels to lay the meatballs on once they have been formed. Repeat until the mixture is all used up.
Mash 4 raw meatballs in dutch oven to brown.
Heat a dutch oven over medium heat with a dollop of oil of choice. Take four of the meatballs and mash them on the bottom of the pan. Let sit for a couple of minutes, untouched, to brown the meat and give it a good sear. This is the beginning of the tomato sauce, and will add more flavour without having to simmer the meatballs in the sauce for hours, risking the meatballs becoming overcooked.
Add onions, seasoning and simmer tomato sauce.
When the mashed meatballs have browned nicely, add onions, dried oregano, crushed tomatoes, and red pepper flakes to the dutch oven. Stir to combine and bring the sauce to a boil. Turn down the heat to low and simmer for 30 minutes.
Brown meatballs in cast iron skillet.
While the tomato sauce is simmering, cook the meatballs in a cast iron skillet. Heat a cast iron skillet over medium heat and add a dollop of oil if choice (high smoke point preferred). When the pan and oil is hot, add the meatballs onto the skillet one by one, arranging them clockwise, from outer rim to the inside. Continue to brown meatballs on all sides until you get a nice crust and a dark golden brown colour.
Simmer meatballs in sauce for 10 mins.
Transfer the meatballs into the dutch oven with the tomato sauce and simmer for 10 minutes. Serve over cooked pasta and garnish with grated parmesan and parsley. Congrats! You just made spaghetti and meatballs.