Heat 1/4 cup olive oil on high heat in a pan and add onions and garlic. Stir frequently until tender. Reduce heat and add canned tomatoes and tablespoon of butter. Let simmer for one hour, stirring occasionally.
In a large bowl mix the pork and beef. In a separate bowl soak the bread in milk and fold that into the meat. Then add the dried seasoning, eggs and bread crumbs. Mix thoroughly until all the elements are blended together.
Form the meat into three ounce balls. In a skillet heat the remaining oil and sear off the meatballs on both sides in batches of four to ensure you don't overcrowd the pan. Cook for about three minutes per side and use a spoon to baste the meatballs to help brown the entire ball.
Once you have seared all the meatballs, place them into sauce on a low simmer for one to two hours until tender. To build your sandwich, spread bomba sauce on both sides of the bread roll, then layer with cheese, fill with saucy meatballs and lightly olive oil and salt dressed arugula. Finish with fresh parmesan cheese.